1
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Kowalczyk NS, Prochaska ML, Worcester EM. Metabolomic profiles and pathogenesis of nephrolithiasis. Curr Opin Nephrol Hypertens 2023; 32:490-495. [PMID: 37530089 PMCID: PMC10403267 DOI: 10.1097/mnh.0000000000000903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
PURPOSE OF REVIEW Kidney stone disease is caused by supersaturation of urine with certain metabolites and minerals. The urine composition of stone formers has been measured to prevent stone recurrence, specifically calcium, uric acid, oxalate, ammonia, citrate. However, these minerals and metabolites have proven to be unreliable in predicting stone recurrence. Metabolomics using high throughput technologies in well defined patient cohorts can identify metabolites that may provide insight into the pathogenesis of stones as well as offer possibilities in therapeutics. RECENT FINDINGS Techniques including 1H-NMR, and liquid chromatography paired with tandem mass spectroscopy have identified multiple possible metabolites involved in stone formation. Compared to formers of calcium oxalate stones, healthy controls had higher levels of hippuric acid as well as metabolites involved in caffeine metabolism. Both the gut and urine microbiome may contribute to the altered metabolome of stone formers. SUMMARY Although metabolomics has offered several potential metabolites that may be protective against or promote stone formation, the mechanisms behind these metabolomic profiles and their clinical significance requires further investigation.
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2
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Dhillon-Jhattu S, McGill RL, Ennis JL, Worcester EM, Zisman AL, Coe FL. Vitamin D and Parathyroid Hormone Levels in CKD. Am J Kidney Dis 2023; 81:122-124. [PMID: 35926776 DOI: 10.1053/j.ajkd.2022.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 06/15/2022] [Indexed: 12/24/2022]
Affiliation(s)
| | | | - Jennifer L Ennis
- Section of Nephrology, University of Chicago Medicine, Chicago, Illinois
| | - Elaine M Worcester
- Section of Nephrology, University of Chicago Medicine, Chicago, Illinois
| | - Anna L Zisman
- Section of Nephrology, University of Chicago Medicine, Chicago, Illinois
| | - Fredric L Coe
- Section of Nephrology, University of Chicago Medicine, Chicago, Illinois
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3
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Moochhala SH, Worcester EM. Primary hyperoxaluria: the adult nephrologist's point of view. Clin Kidney J 2022; 15:i29-i32. [PMID: 35711295 PMCID: PMC9194796 DOI: 10.1093/ckj/sfac068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Indexed: 11/22/2022] Open
Abstract
In adults, primary hyperoxaluria (PH) does not always present as obviously as in children, leading to delayed or even missed diagnosis. When diagnosed in adulthood, PH usually progresses at a slower rate and the focus is on the prevention of recurrent kidney stones as much as it is on the preservation of renal function. The most tragic presentation is when the diagnosis is made after primary non-function of a renal graft for treating previously unknown renal disease. Recurrent stones, nephrocalcinosis and features of systemic oxalosis can all be presenting features. For these reasons, consideration should be given to screening for this rare condition, using biochemical and/or genetic means, but being careful to exclude common differential diagnoses. Such efforts should be synchronized with diagnostic methods for other rare kidney diseases.
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Affiliation(s)
- Shabbir H Moochhala
- Royal Free and University College Medical School, UCL
Department of Renal Medicine,
London, UK
| | - Elaine M Worcester
- University of Chicago, Nephrology Section, South
Maryland, Chicago, IL, USA
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4
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Williams JC, Al-Awadi H, Muthenini M, Bledsoe SB, El-Achkar T, Evan AP, Coe F, Lingeman JE, Worcester EM. Stone morphology distinguishes two pathways of idiopathic calcium oxalate stone pathogenesis. J Endourol 2021; 36:694-702. [PMID: 34915736 PMCID: PMC9145590 DOI: 10.1089/end.2021.0685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Introduction About 1-in-11 Americans will experience a kidney stone, but underlying causes remain obscure. The objective of the present study was to separate idiopathic calcium oxalate stone formers by whether or not they showed positive evidence of forming a stone on Randall's plaque (RP). Materials and Methods In patients undergoing either percutaneous or ureteroscopic procedures for kidney stone removal, all stone material was extracted, and analyzed using micro computed tomographic imaging (micro CT), in order to identify those attached to RP. 24-hour urines were collected weeks after the stone removal procedure and off of medications that would affect urine composition. Endoscopic video was analyzed for papillary pathology (RP, pitting, plugging, dilated ducts, loss of papillary shape) by an observer blinded to the data on stone type. Percent papillary area occupied by RP and ductal plugging was quantified using image analytic software. Results Patients having even 1 stone on RP (N=36) did not differ from Non-RP patients (N=37) in age, sex, BMI, or other clinical characteristics. Compared to the Non-RP group, RP stone formers had more numerous but smaller stones, more abundant papillary RP, and fewer ductal plugs, both by quantitative measurement of surface area (on average, 3 times more plaque area, but only 41% as much plug area as Non-RP) and by semi-quantitative visual grading. Serum and blood values did not differ between RP and Non-RP stone formers by any measure. Conclusions Growth of many small stones on plaque seems the pathogenetic scheme for the RP stone forming phenotype, whereas the Non-RP phenotype stone pathogenesis pathway is less obvious. Higher papillary plugging in Non-RP suggests that plugs play a role in stone formation, and that these patients have a greater degree of papillary damage. Underlying mechanisms that create these distinctive phenotypes are presently unknown.
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Affiliation(s)
- James C Williams
- Indiana University School of Medicine, Department of Anatomy, Cell Biology & Physiology, Indianapolis, Indiana, United States;
| | - Haider Al-Awadi
- Indiana University School of Medicine, Department of Anatomy, Cell Biology & Physiology, Indianapolis, Indiana, United States;
| | - Manognya Muthenini
- Indiana University School of Medicine, Department of Medicine, Indianapolis, Indiana, United States;
| | - Sharon B Bledsoe
- Indiana University School of Medicine, Anatomy, Cell Biology & Physiology, Indianapolis, Indiana, United States;
| | - Tarek El-Achkar
- Indiana University School of Medicine, Department of Medicine , Indianapolis, Indiana, United States;
| | - Andrew P Evan
- indiana University School of Medicine, Anatomy, Cell Biology & Physiology, Indianapolis, Indiana, United States;
| | - Fred Coe
- University of Chicago Pritzker School of Medicine, 12246, Medicine, Chicago, Illinois, United States;
| | - James E Lingeman
- Indiana University School of Medicine, Dept. of Urology, Indianapolis, Indiana, United States;
| | - Elaine M Worcester
- The University of Chicago, Section of Nephrology, Chicago, Illinois, United States;
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5
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Canela VH, Bledsoe SB, Worcester EM, Lingeman JE, El-Achkar TM, Williams JC. Collagen fibrils and cell nuclei are entrapped within Randall's plaques but not in CaOx matrix overgrowth: A microscopic inquiry into Randall's plaque stone pathogenesis. Anat Rec (Hoboken) 2021; 305:1701-1711. [PMID: 34825513 DOI: 10.1002/ar.24837] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/14/2021] [Accepted: 10/19/2021] [Indexed: 01/28/2023]
Abstract
Calcium oxalate (CaOx) stones can grow attached to the renal papillary calcification known as Randall's plaque. Although stone growth on Randall's plaque is a common phenomenon, this mechanism of stone formation is still poorly understood. The objective of this study was to investigate the microenvironment of mature Randall's plaque, explore its molecular composition and differentiate plaque from CaOx overgrowth using multimodal imaging on demineralized stone sections. Fluorescence imaging showed consistent differences in autofluorescence patterns between Randall's plaque and calcium oxalate overgrowth regions. Second harmonic generation imaging established the presence of collagen only in regions of decalcified Randall's plaque but not in regions of CaOx overgrowth matrix. Surprisingly, in these stone sections we observed cell nuclei with preserved morphology within regions of mature Randall's plaque. These conserved cells had variable expression of vimentin and CD45. The presence of nuclei in mature plaque indicates that mineralization is not necessarily associated with cell death. The markers identified suggest that some of the entrapped cells may be undergoing dedifferentiation or could emanate from a mesenchymal or immune origin. We propose that entrapped cells may play an important role in the growth and maintenance of Randall's plaque. Further characterization of these cells and thorough analyses of the mineralized stone forming renal papilla will be fundamental in understanding the pathogenesis of Randall's plaque and CaOx stone formation.
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Affiliation(s)
- Victor Hugo Canela
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Sharon B Bledsoe
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | | | - James E Lingeman
- Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Tarek M El-Achkar
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - James C Williams
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Prochaska ML, Moe OW, Asplin JR, Coe FL, Worcester EM. Evidence for abnormal linkage between urine oxalate and citrate excretion in human kidney stone formers. Physiol Rep 2021; 9:e14943. [PMID: 34231328 PMCID: PMC9814525 DOI: 10.14814/phy2.14943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Animal models have demonstrated an interactive relationship between the epithelial anion exchanger SLC26A6 and transporter NaDC-1 that regulates citrate and oxalate homeostasis. This relationship is a potential mechanism to protect against kidney stones as higher urine oxalate is accompanied by higher urine citrate but it has not been explored in humans. METHODS We examined 24-h urine data on 13,155 kidney stone forming patients (SF) from separate datasets at the University of Chicago and Litholink, a national laboratory, and 143 non-kidney stone forming participants (NSF) to examine this relationship in humans. We used multivariate linear regression models to examine the association between oxalate and citrate in all study participants and separately in SF and NSF. RESULTS Higher urinary oxalate was associated with higher urinary citrate in both SF and NSF. In NSF, the multivariate adjusted urine citrate excretion was 3.0 (1.5-4.6) (mmol)/creatinine (mmol) per oxalate (mmol)/creatinine (mmol). In SF, the multivariate adjusted urine citrate excretion was 0.3 (0.2-0.4) (mmol)/creatinine (mmol) per oxalate (mmol)/creatinine (mmol). CONCLUSIONS Higher urinary oxalate excretion was associated with higher urinary citrate excretion and this effect was larger in non-kidney stone forming participants compared with those who form kidney stones.
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Affiliation(s)
| | - Orson W. Moe
- Department of Internal MedicineUniversity of Texas Southwestern Medical CenterDallasTXUSA
| | - John R. Asplin
- Litholink CorporationLaboratory Corporation of America® HoldingsItascaILUSA
| | - Fredric L. Coe
- Department of MedicineUniversity of Chicago MedicineChicagoILUSA
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7
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Bergsland KJ, Coe FL, El-Achkar TM, Worcester EM. Increased Urinary Leukocyte Esterase Distinguishes Patients With Brushite Kidney Stones. Kidney Int Rep 2021; 6:1729-1731. [PMID: 34169214 PMCID: PMC8207319 DOI: 10.1016/j.ekir.2021.03.894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 03/17/2021] [Accepted: 03/22/2021] [Indexed: 11/17/2022] Open
Affiliation(s)
- Kristin J. Bergsland
- Department of Medicine, Nephrology Section, University of Chicago, Chicago, Illinois, USA
| | - Fredric L. Coe
- Department of Medicine, Nephrology Section, University of Chicago, Chicago, Illinois, USA
| | - Tarek M. El-Achkar
- Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Elaine M. Worcester
- Department of Medicine, Nephrology Section, University of Chicago, Chicago, Illinois, USA
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8
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Borofsky MS, Handa RK, Evan AP, Williams JC, Bledsoe S, Coe FL, Worcester EM, Lingeman JE. In Vivo Renal Tubule pH in Stone-Forming Human Kidneys. J Endourol 2021; 34:203-208. [PMID: 31760802 DOI: 10.1089/end.2019.0378] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Introduction: There is evidence that patients with a history of ileostomies, who produce acidic urine and form uric acid or calcium oxalate stones, may plug some collecting ducts with calcium phosphate (CaP) and urate crystals. This is a paradoxical finding as such minerals should not form at an acid pH. One possible explanation is the presence of acidification defects due to focal damage to inner medullary collecting duct and Bellini duct (BD) cells. We sought to further investigate this hypothesis through direct measurement of ductal pH in dilated BDs in patients with ileostomies undergoing percutaneous nephrolithotomy (PCNL) for stone removal. Methods: After obtaining institutional review board approval, we used a fiber-optic pH microsensor with a 140-μm-diameter tip to measure intraluminal pH from the bladder, saline irrigant, and dilated BDs of patients undergoing PCNL. Results: Measurements were taken from three patients meeting inclusion criteria. Measured pH of bladder urine ranged from 4.97 to 5.58 and pH of saline irrigant used during surgery ranged from 5.17 to 5.75. BD measurements were achieved in 11 different BDs. Mean intraductal BD pH was more than 1 unit higher than bulk urine (6.43 ± 0.22 vs 5.31 ± 0.22, p < 0.01). Conclusions: This is the first evidence for focal acidification defects within injured/dilated BDs of human kidneys producing highly acidic bulk phase urine. These results may help explain the paradoxical finding of CaP and urate plugs in dilated ducts of patients with stone-forming diseases characterized by highly acidic urine.
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Affiliation(s)
- Michael S Borofsky
- Department of Urology, Indiana University Health at Methodist Hospital, Indianapolis, Indiana
| | - Rajash K Handa
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - James C Williams
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Sharon Bledsoe
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Fredric L Coe
- Section of Nephrology, Department of Medicine, University of Chicago, Chicago, Illinois
| | - Elaine M Worcester
- Section of Nephrology, Department of Medicine, University of Chicago, Chicago, Illinois
| | - James E Lingeman
- Department of Urology, Indiana University Health at Methodist Hospital, Indianapolis, Indiana
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9
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Canela VH, Bledsoe SB, Lingeman JE, Gerber G, Worcester EM, El‐Achkar TM, Williams JC. Demineralization and sectioning of human kidney stones: A molecular investigation revealing the spatial heterogeneity of the stone matrix. Physiol Rep 2021; 9:e14658. [PMID: 33403824 PMCID: PMC7786195 DOI: 10.14814/phy2.14658] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 11/24/2022] Open
Abstract
The molecular mechanisms by which kidney stones grow are largely unknown. Organic molecules from the urine combine with mineral crystals to form stones, but analysis of the stone matrix has revealed over a thousand different proteins, with no clues as to which are important for stone growth. Molecules that are present in every layer of a stone would be candidates for having an essential function, and thus the analysis of the stone matrix at a microscopic level is necessary. For this purpose, kidney stones were demineralized, sectioned, stained, and imaged by microscopy, using micro CT for precise orientation. Histological staining demonstrated heterogeneity in the density of adjacent layers within stones. Additional results also showed brilliant and unique autofluorescence patterns in decalcified nephroliths, indicating heterogeneous organic composition in adjacent layers. Regions of calcium oxalate (CaOx) stones were dissected using laser microdissection (LMD) for protein analysis. LMD of broad regions of demineralized CaOx stone sections yielded the same proteins as those found in different specimens of pulverized CaOx stones. These innovative methodologies will allow spatial mapping of protein composition within the heterogeneous stone matrix. Proteins that consistently coincide spatially with mineral deposition would be candidates for molecules essential for stone growth. This kind of analysis will be required to assess which of the thousand proteins in the stone matrix may be fundamental for stone growth.
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Affiliation(s)
- Victor Hugo Canela
- Department of Anatomy, Cell Biology & PhysiologyIndiana University School of MedicineIndianapolisINUSA
| | - Sharon B. Bledsoe
- Department of Anatomy, Cell Biology & PhysiologyIndiana University School of MedicineIndianapolisINUSA
| | - James E. Lingeman
- Department of UrologyIndiana University School of MedicineIndianapolisINUSA
| | - Glenn Gerber
- Section of NephrologyDepartment of MedicineUniversity of ChicagoChicagoILUSA
| | - Elaine M. Worcester
- Section of NephrologyDepartment of MedicineUniversity of ChicagoChicagoILUSA
| | - Tarek M. El‐Achkar
- Department of Anatomy, Cell Biology & PhysiologyIndiana University School of MedicineIndianapolisINUSA
- Division of NephrologyDepartment of MedicineIndiana University and Roudebush Indianapolis Veterans Affairs Medical CenterIndianapolisINUSA
| | - James C. Williams
- Department of Anatomy, Cell Biology & PhysiologyIndiana University School of MedicineIndianapolisINUSA
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10
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Winfree S, Weiler C, Bledsoe SB, Gardner T, Sommer AJ, Evan AP, Lingeman JE, Krambeck AE, Worcester EM, El-Achkar TM, Williams JC. Multimodal imaging reveals a unique autofluorescence signature of Randall's plaque. Urolithiasis 2020; 49:123-135. [PMID: 33026465 DOI: 10.1007/s00240-020-01216-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/25/2020] [Indexed: 12/01/2022]
Abstract
Kidney stones frequently develop as an overgrowth on Randall's plaque (RP) which is formed in the papillary interstitium. The organic composition of RP is distinct from stone matrix in that RP contains fibrillar collagen; RP in tissue has also been shown to have two proteins that are also found in stones, but otherwise the molecular constituents of RP are unstudied. We hypothesized that RP contains unique organic molecules that can be differentiated from the stone overgrowth by fluorescence. To test this, we used micro-CT-guided polishing to expose the interior of kidney stones for multimodal imaging with multiphoton, confocal and infrared microscopy. We detected a blue autofluorescence signature unique to RP, the specificity of which was also confirmed in papillary tissue from patients with stone disease. High-resolution mineral mapping of the stone also showed a transition from the apatite within RP to the calcium oxalate in the overgrowth, demonstrating the molecular and spatial transition from the tissue to the urine. This work provides a systematic and practical approach to uncover specific fluorescence signatures which correlate with mineral type, verifies previous observations regarding mineral overgrowth onto RP and identifies a novel autofluorescence signature of RP demonstrating RP's unique molecular composition.
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Affiliation(s)
- Seth Winfree
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Courtney Weiler
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Sharon B Bledsoe
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Tony Gardner
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - André J Sommer
- Molecular Microspectroscopy Laboratory, Department of Chemistry and Biochemistry, Miami University, Oxford, OH, USA
| | - Andrew P Evan
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - James E Lingeman
- Department of Urology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Amy E Krambeck
- Department of Urology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Elaine M Worcester
- Division of Nephrology, Department of Medicine, University of Chicago, Chicago, IL, USA
| | - Tarek M El-Achkar
- Division of Nephrology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - James C Williams
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, IN, USA.
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11
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Zisman AL, Coe FL, Cohen AJ, Riedinger CB, Worcester EM. Racial Differences in Risk Factors for Kidney Stone Formation. Clin J Am Soc Nephrol 2020; 15:1166-1173. [PMID: 32561654 PMCID: PMC7409744 DOI: 10.2215/cjn.12671019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 05/15/2020] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES Incidence of kidney stone disease is rising. It is not known whether mechanisms of stone formation differ across racial groups. Our objective was to identify differing lithogenic risk factors across racial groups in idiopathic nephrolithiasis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We conducted a retrospective cohort study evaluating metabolic risk factors in black and age-matched white idiopathic stone formers at our tertiary referral center. We compared serum and urine metabolic risk factors pre- and post-treatment across racial groups using analysis of covariance. Generalized linear modeling was used to build regression models for risk of stone formation in both groups. RESULTS Among 117 black and 172 white stone formers, urine volume was lower in black stone formers (1.4±0.8 versus 2.0±0.8 L/d, P<0.001). Urine calcium was lower in black stone formers (116±70 versus 217±115 mg/d, P<0.001). Supersaturations for calcium oxalate were similar among the groups, whereas calcium phosphate supersaturation was higher in white stone formers, and uric acid supersaturation was higher in black stone formers. Electrolyte free water clearance was significantly lower in black stone formers (207±780 versus 435±759 ml/d, P=0.02). In the subgroup of 77 black patients and 107 white patients with post-treatment evaluations, urine volume rose significantly and similarly in both groups. Urine sodium was unchanged in whites but increased in blacks by 40 mmol/d (95% confidence interval, 32 to 48 mmol/d). Electrolyte free water clearance remained lower in black stone formers (385±891 versus 706±893 ml/d, P=0.02). Post-treatment supersaturations were similar across the groups except for calcium phosphate, which improved with treatment in whites. CONCLUSIONS Black stone formers have lower 24-hour urine calcium excretion and urine volume. Increases in urine volume with treatment were associated with increased solute, but not free water, excretion in black stone formers.
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Affiliation(s)
- Anna L Zisman
- Department of Medicine, Section of Nephrology, University of Chicago, Chicago, Illinois
| | - Fredric L Coe
- Department of Medicine, Section of Nephrology, University of Chicago, Chicago, Illinois
| | - Andrew J Cohen
- Brady Urological Institute, Johns Hopkins University, Baltimore, Maryland
| | | | - Elaine M Worcester
- Department of Medicine, Section of Nephrology, University of Chicago, Chicago, Illinois
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12
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Makki MS, Winfree S, Lingeman JE, Witzmann FA, Worcester EM, Krambeck AE, Coe FL, Evan AP, Bledsoe S, Bergsland KJ, Khochare S, Barwinska D, Williams JC, El-Achkar TM. A Precision Medicine Approach Uncovers a Unique Signature of Neutrophils in Patients With Brushite Kidney Stones. Kidney Int Rep 2020; 5:663-677. [PMID: 32405588 PMCID: PMC7210605 DOI: 10.1016/j.ekir.2020.02.1025] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 02/10/2020] [Indexed: 12/22/2022] Open
Abstract
Introduction We have previously found that papillary histopathology differs greatly between calcium oxalate and brushite stone formers (SF); the latter have much more papillary mineral deposition, tubular cell injury, and tissue fibrosis. Methods In this study, we applied unbiased orthogonal omics approaches on biopsied renal papillae and extracted stones from patients with brushite or calcium oxalate (CaOx) stones. Our goal was to discover stone type-specific molecular signatures to advance our understanding of the underlying pathogenesis. Results Brushite SF did not differ from CaOx SF with respect to metabolic risk factors for stones but did exhibit increased tubule plugging in their papillae. Brushite SF had upregulation of inflammatory pathways in papillary tissue and increased neutrophil markers in stone matrix compared with those with CaOx stones. Large-scale 3-dimensional tissue cytometry on renal papillary biopsies showed an increase in the number and density of neutrophils in the papillae of patients with brushite versus CaOx, thereby linking the observed inflammatory signatures to the neutrophils in the tissue. To explain how neutrophil proteins appear in the stone matrix, we measured neutrophil extracellular trap (NET) formation—NETosis—and found it significantly increased in the papillae of patients with brushite stones compared with CaOx stones. Conclusion We show that increased neutrophil infiltration and NETosis is an unrecognized factor that differentiates brushite and CaOx SF and may explain the markedly increased scarring and inflammation seen in the papillae of patients with brushite stones. Given the increasing prevalence of brushite stones, the role of neutrophil activation in brushite stone formation requires further study.
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Affiliation(s)
- Mohammad Shahidul Makki
- Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Seth Winfree
- Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Cellular & Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - James E Lingeman
- Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Frank A Witzmann
- Department of Cellular & Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Elaine M Worcester
- Department of Medicine, Division of Nephrology, University of Chicago, Chicago, Illinois, USA
| | - Amy E Krambeck
- Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Fredric L Coe
- Department of Medicine, Division of Nephrology, University of Chicago, Chicago, Illinois, USA
| | - Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Sharon Bledsoe
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Kristin J Bergsland
- Department of Medicine, Division of Nephrology, University of Chicago, Chicago, Illinois, USA
| | - Suraj Khochare
- Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Daria Barwinska
- Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - James C Williams
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Tarek M El-Achkar
- Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Cellular & Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Evan AP, Coe FL, Worcester EM, Williams JC, Heiman J, Bledsoe S, Sommer A, Philips CL, Lingeman JE. Discrepancy Between Stone and Tissue Mineral Type in Patients with Idiopathic Uric Acid Stones. J Endourol 2020; 34:385-393. [PMID: 31880949 DOI: 10.1089/end.2019.0564] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Objectives: To describe the papillary pathology found in uric acid (UA) stone formers, and to investigate the mineral form of tissue deposits. Materials and Methods: We studied eight UA stone formers treated with percutaneous nephrolithotomy. Papillae were imaged intraoperatively using digital endoscopy, and cortical and papillary biopsies were taken. Biopsies were analyzed by light microscopy, micro-CT, and microinfrared spectroscopy. Results: As expected, urine pH was generally low. UA supersaturation exceeded one in all but one case, compatible with the stone material. By intraoperative imaging, the renal papillae displayed a heterogeneous mixture of plaque and plugging, ranging from normal to severe. All patients had mineral in ducts of Bellini and inner medullary collecting ducts, mainly apatite with lesser amounts of urate and/or calcium oxalate in some specimens. Papillary and cortical interstitial tissue injury was modest despite the tubule plugging. No instance was found of a stone growing attached to either plaque or plugs. Conclusions: UA stone formers resemble those with ileostomy in having rather low urine pH while forming tubule plugs that contain crystals that can only form at pH values above those of their bulk urine. This discrepancy between tissue mineral deposits and stone type suggests that local tubular pH exceeds that of the bulk urine, perhaps because of localized tubule injury. The manner in which UA stones form and the discordance between tubule crystals and stone type remain open research questions.
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Affiliation(s)
- Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Fredric L Coe
- Department of Medicine, University of Chicago, Chicago, Illinois
| | | | - James C Williams
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Joshua Heiman
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Sharon Bledsoe
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Andre Sommer
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio
| | - Carrie L Philips
- Department of Pathology, Indiana University Health Partners, Indianapolis, Indiana
| | - James E Lingeman
- Department of Urology, International Kidney Stone Institute, Indiana University Health Partners, Indianapolis, Indiana
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Worcester EM, Bergsland KJ, Gillen DL, Coe FL. Evidence for disordered acid-base handling in calcium stone-forming patients. Am J Physiol Renal Physiol 2020; 318:F363-F374. [PMID: 31790303 DOI: 10.1152/ajprenal.00400.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In stone formers (SFs) with idiopathic hypercalciuria, urine pH governs the mineral phase of stones. Calcium phosphate (CaP) SFs have higher urine pH than calcium oxalate (CaOx) SFs. Normal women have higher urine pH than men on fixed diets, accompanied by greater absorption of food alkali. Female CaP and male CaOx SFs have similar urine pH as same sex normal individuals, but male CaP and female CaOx SFs may have abnormal acid-base handling. We studied 25 normal individuals (13 men and 12 women), 17 CaOx SFs (11 men and 6 women), and 15 CaP SFs (8 men and 7 women) on fixed diets. Urine and blood samples were collected under fasting and fed conditions. Female CaOx SFs had lower urine pH and lower alkali absorption, fed, compared with normal women; their urine NH4 was higher and urine citrate excretion lower than in normal women, consistent with their higher net acid excretion. Male CaOx SFs had higher urine citrate excretion and higher serum ultrafilterable citrate levels than normal men. Both male and female CaP SFs had higher urine pH fasting than same sex normal individuals, but only men were higher in the fed period, and there were no differences from normal in gut alkali absorption. CaP SFs of both sexes had higher urine NH4 and lower urine citrate than same sex normal individuals. The lower urine pH of female CaOx SFs seems related to decreased gut alkali absorption, while the higher pH of CaP SFs, accompanied by higher urine NH4 and lower urine citrate, suggests a proximal tubule disorder.
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Affiliation(s)
- Elaine M Worcester
- Department of Medicine, University of Chicago Medicine, Chicago, Illinois
| | | | - Daniel L Gillen
- Department of Statistics, University of California, Irvine, California
| | - Fredric L Coe
- Department of Medicine, University of Chicago Medicine, Chicago, Illinois
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15
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Abstract
One of the main functions of the kidney is to excrete an acid load derived from both dietary and endogenous sources, thus maintaining the pH of other fluids in the body. Urine pH is also of particular interest in stone formers, since it determines the presence of either calcium phosphate or uric acid content in stones. Others have noted in epidemiological studies a rise in incidence of low pH-dependent uric acid stones with age, coinciding with a decrease in the incidence of high pH-dependent phosphate stones. Taken together, these trends are suggestive of a longitudinal decline in urine pH in stone-forming patients, and, if true, this could explain the observed trends in stone incidence. We studied 7,891 stone formers, all of whom collected a 24-h urine sample and matching serum. Multivariate modeling revealed that urine pH did indeed fall with age and particularly between the ages of 20 and 50 yr old in both men and women. We sought to explain this trend through the inclusion of traditionally understood determinants of urine pH such as urinary buffers, estimates of glomerular filtration, and dietary acid load, but these, taken together, accounted for but a small fraction of the pH fall. Gastrointestinal anion absorption was the strongest predictor of urine pH in all age groups, as we have previously reported in middle-aged normal men and women. However, we found that, despite a decreasing urine pH, gastrointestinal anion absorption increased monotonically with age. In fact, after adjustment for gastrointestinal anion absorption, urine pH declined more markedly, suggesting that bicarbonate-producing anion absorption is regulated in a manner that offsets the decline of urine pH.
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Affiliation(s)
- Cameron J Menezes
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
| | - Elaine M Worcester
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
| | - Fredric L Coe
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
| | - John Asplin
- Litholink, Laboratory Corporation of America Holdings , Chicago, Illinois
| | | | - Benjamin Ko
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
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Evan AP, Coe FL, Lingeman J, Bledsoe S, Worcester EM. Randall's plaque in stone formers originates in ascending thin limbs. Am J Physiol Renal Physiol 2018; 315:F1236-F1242. [PMID: 30066583 DOI: 10.1152/ajprenal.00035.2018] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Randall's plaque, an attachment site over which calcium oxalate stones form, begins in the basement membranes of thin limbs of the loop of Henle. The mechanism of its formation is unknown. Possibly, enhanced delivery of calcium out of the proximal tubule, found in many stone formers, increases reabsorption of calcium from the thick ascending limb into the interstitium around descending vasa recta, which convey that calcium into the deep medulla, and raises supersaturations near thin limbs ("vas washdown"). According to this hypothesis, plaque should form preferentially on ascending thin limbs, which do not reabsorb water. We stained serial sections of papillary biopsies from stone-forming patients for aquaporin 1 (which is found in the descending thin limb) and the kidney-specific chloride channel ClC-Ka (which is found in the ascending thin limb). Plaque (which is detected using Yasue stain) colocalized with ClC-Ka, but not with aquaporin 1 (χ2 = 464, P < 0.001). We conclude that plaque forms preferentially in the basement membranes of ascending thin limbs, fulfilling a critical prediction of the vas washdown theory of plaque pathogenesis. The clinical implication is that treatments such as a low-sodium diet or thiazide diuretics that raise proximal tubule calcium reabsorption may reduce formation of plaque as well as calcium kidney stones.
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Affiliation(s)
- Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Fredric L Coe
- Nephrology Section, Department of Medicine, University of Chicago , Chicago, Illinois
| | - James Lingeman
- Department of Urology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Sharon Bledsoe
- Department of Anatomy and Cell Biology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Elaine M Worcester
- Nephrology Section, Department of Medicine, University of Chicago , Chicago, Illinois
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Bergsland KJ, Coe FL, Parks JH, Asplin JR, Worcester EM. Evidence for a role of PDZ domain-containing proteins to mediate hypophosphatemia in calcium stone formers. Nephrol Dial Transplant 2018; 33:759-770. [PMID: 29126251 DOI: 10.1093/ndt/gfx284] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 08/29/2017] [Indexed: 01/26/2023] Open
Abstract
Background Hypophosphatemia (HYP) is common among calcium stone formers (SFs) and in rare cases is associated with mutations in sodium-phosphate cotransporters or in Na+/H+ exchanger regulatory factor 1 (NHERF1), but the majority of cases are unexplained. We hypothesized that reduced sodium-phosphate cotransporter activity mediated via NHERF1 or a similar PDZ domain-containing protein, causes HYP. If so, other transport activities controlled by NHERF1, such as NHE3 and URAT1, might be reduced in HYP. Methods To test this idea, we analyzed two large but separate sets of 24-h urine samples and paired serums of 2700 SFs from the University of Chicago and 11 073 SFs from Litholink, a national laboratory. Patients were divided into quintiles based on serum phosphate. Results Males were more common in the lowest phosphate tiles in both datasets. Phosphate excretion did not vary across the quintiles, excluding diet as a cause of HYP. Tubule maximum (Tm) phosphate per unit glomerular filtration rate decreased and fractional excretion increased with decreasing phosphate quintiles, indicating reduced tubule phosphate reabsorption was responsible for HYP. Urine pH and serum chloride increased with decreasing serum phosphate, suggesting a coordinate change in NHE3 activity. Serum uric acid and Tm uric acid decreased significantly with decreasing serum phosphate, while uric acid excretion did not vary. Conclusion. HYP in SFs results from decreased tubule phosphate reabsorption and, being associated with related changes in other proximal tubule transporters, may arise from alterations in or signaling to PDZ-containing proteins.
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Affiliation(s)
| | - Fredric L Coe
- Department of Medicine, University of Chicago, Chicago, IL, USA
| | - Joan H Parks
- Department of Medicine, University of Chicago, Chicago, IL, USA
| | - John R Asplin
- Litholink Corporation, Laboratory Corporation of America Holdings, Chicago, IL, USA
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Riedinger CB, Anderson BB, Adamsky MA, Cohen AJ, Gerber GS, Worcester EM, Coe FL, Zisman AL. MP13-20 THE RELATIONSHIP BETWEEN PAPILLARY GRADING AND METABOLIC RISK FACTORS FOR STONE FORMATION. J Urol 2018. [DOI: 10.1016/j.juro.2018.02.492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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19
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Abstract
Regulation of acid-base metabolism maintains the pH of body fluids within a tight range. Urine pH (UpH) is also regulated under normal conditions. Median pH of 24-h urines is ~6, but others have noted that UpH in women is higher than men, which has been attributed to differences in diet. If true, it would help to explain the fact that calcium phosphate stones, which form at higher urine pH, are much more common in women than in men. We studied 14 normal subjects (7 men and 7 women) fed identical meals in a Clinical Research Center. Urine and blood samples were collected during fasting and after meals. UpH of women (6.74 ± 0.11) exceeded that of men (6.07 ± 0.17) fed, but not fasting, and UpH rose significantly with meals in women but not men. Serum and urine total CO2 rose with meals in women but not men, and in women net acid excretion fell to zero during the fed period. In a general linear model adjusted for age, sex, and weight, net gastrointestinal anion uptake was the main predictor of UpH and was significantly higher in women (3.9 ± 0.6) than men (1.8 ± 0.7) in the fed period. Urine citrate, an anion absorbed by the gastrointestinal tract, was higher in women than men in the fed state, and fractional excretion of citrate was higher in women than men. The higher fed UpH in women is related to a greater absorption of food anions and raises 24-h UpH.
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Affiliation(s)
- Elaine M Worcester
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
| | | | - Daniel L Gillen
- Department of Statistics, University of California , Irvine, California
| | - Fredric L Coe
- Department of Medicine, University of Chicago Medicine , Chicago, Illinois
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20
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Williams JC, Borofsky MS, Bledsoe SB, Evan AP, Coe FL, Worcester EM, Lingeman JE. Papillary Ductal Plugging is a Mechanism for Early Stone Retention in Brushite Stone Disease. J Urol 2017; 199:186-192. [PMID: 28822796 DOI: 10.1016/j.juro.2017.08.063] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/09/2017] [Indexed: 11/17/2022]
Abstract
PURPOSE Mechanisms of early stone retention in the kidney are under studied and poorly understood. To date attachment via Randall's plaque is the only widely accepted theory in this regard, which is best described in idiopathic calcium oxalate stone formers. Brushite stone formers are known to have distinct papillary morphology relative to calcium oxalate stone formers. As such we sought to determine whether stone attachment mechanisms in such patients may be similarly unique. MATERIALS AND METHODS Patients undergoing percutaneous and or ureteroscopic procedures for stone removal consented to endoscopic renal papillary examination and individual stone collection. Each removed stone was processed using micro computerized tomography to assess the 3-dimensional microstructure and the minerals contained, and search for common structural features indicative of novel mechanisms of early growth and attachment to renal tissue. RESULTS A total of 25 intact brushite stones were removed from 8 patients and analyzed. Video confirmed attachment of 13 of the 25 stones with the remainder believed to have been accidently dislodged during the procedure. Microscopic examination by light and computerized tomography failed to show evidence of Randall's plaque associated with any stone containing brushite. Conversely each brushite stone demonstrated microstructural evidence of having grown attached to a ductal plug formed of apatite. CONCLUSIONS Three-dimensional analysis of small brushite stones suggests overgrowth on ductal apatite plugs as a mechanism of early stone growth and retention. Such findings represent what is to our knowledge the initial supporting evidence for a novel mechanism of stone formation which has previously been hypothesized but never verified.
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Affiliation(s)
- James C Williams
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana.
| | | | - Sharon B Bledsoe
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Fredric L Coe
- Section of Nephrology, University of Chicago, Chicago, Illinois
| | | | - James E Lingeman
- Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana
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Borofsky MS, Williams JC, Worcester EM, Dauw CA, York NE, Evan AP, Lingeman JE. MP19-14 MECHANISTIC EVIDENCE THAT PAPILLARY PITS OCCUR SECONDARY TO DISLODGEMENT OF RANDALL’S PLAQUE ATTACHED STONES. J Urol 2017. [DOI: 10.1016/j.juro.2017.02.3256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Cohen AJ, Borofsky MS, Anderson BB, Dauw CA, Gillen DL, Gerber GS, Worcester EM, Coe FL, Lingeman JE. Endoscopic Evidence That Randall's Plaque is Associated with Surface Erosion of the Renal Papilla. J Endourol 2016; 31:85-90. [PMID: 27824271 DOI: 10.1089/end.2016.0537] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVE This study was conducted to assess the reliability and precision of an endoscopic grading scale to identify renal papillary abnormalities across a spectrum of equipment, locations, graders, and patients. MATERIALS AND METHODS Intra- and interobserver reliability of the papillary grading system was assessed using weighted kappa scoring among 4 graders reviewing a single renal papilla from 50 separate patients on 2 occasions. Grading was then applied to a cohort of patients undergoing endoscopic stone removal procedures at two centers. Patient factors were compared with papillary scores on the level of the papilla, kidney, and patient. RESULTS Graders achieved substantial (kappa >0.6) intra- and inter-rater reliability in scored domains of ductal plugging, surface pitting, and loss of contour. Agreement for Randall's Plaque (RP) was moderate. Papillary scoring was then performed for 76 patients (89 kidneys, 533 papillae). A significant association was discovered between pitting and RP that held both within and across institutions. A general linear model was then created to further assess this association and it was found that RP score was a highly significant independent correlate of pitting score (F = 7.1; p < 0.001). Mean pitting scores increased smoothly and progressively with increasing RP scores. Sums of the scored domains were then calculated as a reflection of gross papillary abnormality. When analyzed in this way, a history of stone recurrence and shockwave lithotripsy were strongly predictive of higher sums. CONCLUSIONS Renal papillary pathology can be reliably assessed between different providers using a newly described endoscopic grading scale. Application of this scale to stone-forming patients suggests that the degree of RP appreciated in the papilla is strongly associated with the presence of pitting. It also suggests that patients with a history of recurrent stones and lithotripsy have greater burdens of gross papillary disease.
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Affiliation(s)
- Andrew J Cohen
- 1 Section of Urology, Department of Surgery University of Chicago , Chicago, Illinois
| | - Michael S Borofsky
- 2 Department of Urology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Blake B Anderson
- 1 Section of Urology, Department of Surgery University of Chicago , Chicago, Illinois
| | - Casey A Dauw
- 2 Department of Urology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Daniel L Gillen
- 3 Department of Statistics, Program in Public Health, and Department of Epidemiology, University of California , California, Irvine
| | - Glenn S Gerber
- 1 Section of Urology, Department of Surgery University of Chicago , Chicago, Illinois
| | | | - Fredric L Coe
- 4 Section of Nephrology, University of Chicago , Chicago, Illinois
| | - James E Lingeman
- 2 Department of Urology, Indiana University School of Medicine , Indianapolis, Indiana
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Abstract
The most common presentation of nephrolithiasis is idiopathic calcium stones in patients without systemic disease. Most stones are primarily composed of calcium oxalate and form on a base of interstitial apatite deposits, known as Randall's plaque. By contrast some stones are composed largely of calcium phosphate, as either hydroxyapatite or brushite (calcium monohydrogen phosphate), and are usually accompanied by deposits of calcium phosphate in the Bellini ducts. These deposits result in local tissue damage and might serve as a site of mineral overgrowth. Stone formation is driven by supersaturation of urine with calcium oxalate and brushite. The level of supersaturation is related to fluid intake as well as to the levels of urinary citrate and calcium. Risk of stone formation is increased when urine citrate excretion is <400 mg per day, and treatment with potassium citrate has been used to prevent stones. Urine calcium levels >200 mg per day also increase stone risk and often result in negative calcium balance. Reduced renal calcium reabsorption has a role in idiopathic hypercalciuria. Low sodium diets and thiazide-type diuretics lower urine calcium levels and potentially reduce the risk of stone recurrence and bone disease.
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Affiliation(s)
- Fredric L Coe
- Nephrology Section MC 5100, University of Chicago Medicine, 5841 S. Maryland Avenue, Chicago, Illinois, 60637 USA
| | - Elaine M Worcester
- Nephrology Section MC 5100, University of Chicago Medicine, 5841 S. Maryland Avenue, Chicago, Illinois, 60637 USA
| | - Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS 5055, Indianapolis, IN 46220, Indiana, USA
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Witzmann FA, Evan AP, Coe FL, Worcester EM, Lingeman JE, Williams JC. Label-free proteomic methodology for the analysis of human kidney stone matrix composition. Proteome Sci 2016; 14:4. [PMID: 26924944 PMCID: PMC4769560 DOI: 10.1186/s12953-016-0093-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 02/19/2016] [Indexed: 11/10/2022] Open
Abstract
Background Kidney stone matrix protein composition is an important yet poorly understood aspect of nephrolithiasis. We hypothesized that this proteome is considerably more complex than previous reports have indicated and that comprehensive proteomic profiling of the kidney stone matrix may demonstrate relevant constitutive differences between stones. We have analyzed the matrices of two unique human calcium oxalate stones (CaOx-Ia and CaOx-Id) using a simple but effective chaotropic reducing solution for extraction/solubilization combined with label-free quantitative mass spectrometry to generate a comprehensive profile of their proteomes, including physicochemical and bioinformatic analysis.` Results We identified and quantified 1,059 unique protein database entries in the two human kidney stone samples, revealing a more complex proteome than previously reported. Protein composition reflects a common range of proteins related to immune response, inflammation, injury, and tissue repair, along with a more diverse set of proteins unique to each stone. Conclusion The use of a simple chaotropic reducing solution and moderate sonication for extraction and solubilization of kidney stone powders combined with label-free quantitative mass spectrometry has yielded the most comprehensive list to date of the proteins that constitute the human kidney stone proteome. Electronic supplementary material The online version of this article (doi:10.1186/s12953-016-0093-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Frank A Witzmann
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, 635 Barnhill Drive, Room 362A, Indianapolis, IN 46202-5120 USA
| | - Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN USA
| | - Fredric L Coe
- Department of Medicine, Nephrology Section, University of Chicago, Chicago, IL USA
| | - Elaine M Worcester
- Department of Medicine, Nephrology Section, University of Chicago, Chicago, IL USA
| | - James E Lingeman
- International Kidney Stone Institute, Methodist Hospital, Indianapolis, IN USA
| | - James C Williams
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN USA
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Borofsky MS, Paonessa JE, Evan AP, Williams JC, Coe FL, Worcester EM, Lingeman JE. Introduction of a Renal Papillary Grading System for Patients with Nephrolithiasis. ACTA ACUST UNITED AC 2015; 29:10.1089/vid.2015.0023. [PMID: 32292640 DOI: 10.1089/vid.2015.0023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 05/28/2015] [Accepted: 06/04/2015] [Indexed: 11/12/2022]
Abstract
Introduction: An overlooked finding at the time of renal endoscopy for patients with nephrolithiasis is the appearance of the renal papillae. Recent work has demonstrated that it is possible to distinguish specific stone-forming phenotypes by endoscopic patterns of papillary appearance alone.1-4 These variable expressions are likely to have clinical significance; yet, the ability to pursue such research efforts remains limited by the lack of a standardized system to describe these findings. Herein, we describe a novel grading system designed to standardize and simplify the description of renal papillary appearance in stone formers at the time of endoscopy. Materials and Methods: Since 1999, 342 patients have been prospectively enrolled and given consent to be part of an NIH funded project studying the pathogenesis of stone formation at a single institution (Methodist Hospital, Indiana University Health). Patients have been treated and studied using both percutaneous and retrograde ureteroscopic approaches. Digital scopes are utilized when feasible along with fluoroscopy to map the affected renal unit(s), and stones are removed and analyzed individually when possible.5 Results: Four recurring abnormal papillary features were identified based upon the collective knowledge and expertise of the primary research team. Each variable was then quantitated based on the severity in appearance. Three features believed to be associated with papillary injury include ductal plugging, pitting, and loss of papillary contour. Ductal plugging is evident as either suburothelial deposits of yellow mineral or as dilated ducts of Bellini, presumably left behind after a plug has passed. These two subfeatures are considered the same for the purposes of grading. Pitting reflects crater-like erosion of the papillary surface. Loss of contour reflects global depression of the papilla relative to the surrounding tissue. Upon papillary inspection, each papilla receives a numerical grade from 0 to 2 for each of these measured domains. The three scores are then added together to create a sum total score regarding the degree of papillary injury ranging from 0 to 6. The fourth feature, the amount of Randall's plaque, is evident as white deposits along the papillary surface. It is not known to cause papillary injury6 and, as such, is designated with an alphabetical subscore (a-c) rather than a number. Each papilla then receives a final unique score incorporating both the sum numerical and alphabetical grade. Reference examples are shown in the accompanying video. Conclusions: The creation of a standardized system to describe the papillary appearance in stone formers has considerable clinical and academic utility. On a clinical level, it could be applied as a tool to document intraoperative findings and determine changes in papillary appearance over time in recurrent stone formers. It also has the potential to distinguish high-risk patients with more pressing needs of metabolic evaluations, medical therapy, and surveillance imaging. As a research tool, it would help create a common language to describe papillary appearance and improve collaboration between researchers. It also might allow surgeons to better correlate endoscopic findings to pathological findings and clinical outcomes such as stone analysis, associated metabolic diseases, risk of progressive renal injury, and stone recurrence. No competing financial interests exist. Accompanying manuscript submitted to Journal of Endourology (END-2015-0298; in review). Runtime of video: 5 mins 37 secs.
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Affiliation(s)
| | - Jessica E Paonessa
- Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - James C Williams
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Fredric L Coe
- Section of Nephrology, The University of Chicago, Chicago, Illinois
| | | | - James E Lingeman
- Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana
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Borofsky MS, Paonessa JE, Evan AP, Williams JC, Coe FL, Worcester EM, Lingeman JE. A Proposed Grading System to Standardize the Description of Renal Papillary Appearance at the Time of Endoscopy in Patients with Nephrolithiasis. J Endourol 2015; 30:122-7. [PMID: 26414908 DOI: 10.1089/end.2015.0298] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND AND PURPOSE The appearance of the renal papillae in patients with nephrolithiasis can be quite variable and can range from entirely healthy to markedly diseased. The implications of such findings remain unknown. One potential reason is the lack of a standardized system to describe such features. We propose a novel grading scale to describe papillary appearance at the time of renal endoscopy. METHODS Comprehensive endoscopic renal assessment and mapping were performed on more than 300 patients with nephrolithiasis. Recurring abnormal papillary characteristics were identified and quantified based on degree of severity. RESULTS Four unique papillary features were chosen for inclusion in the PPLA scoring system- ductal Plugging, Pitting, Loss of contour, and Amount of Randall's plaque. Unique scores are calculated for individual papillae based on reference examples. CONCLUSIONS The description and study of renal papillary appearance in stone formers have considerable potential as both a clinical and research tool; however, a standardized grading system is necessary before using it for these purposes.
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Affiliation(s)
- Michael S Borofsky
- 1 Department of Urology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Jessica E Paonessa
- 1 Department of Urology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Andrew P Evan
- 2 Department of Anatomy and Cell Biology, Indiana University School of Medicine , Indianapolis, Indiana
| | - James C Williams
- 2 Department of Anatomy and Cell Biology, Indiana University School of Medicine , Indianapolis, Indiana
| | - Fredric L Coe
- 3 Section of Nephrology, The University of Chicago , Chicago, Illinois
| | | | - James E Lingeman
- 1 Department of Urology, Indiana University School of Medicine , Indianapolis, Indiana
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Ko B, Bergsland K, Gillen DL, Evan AP, Clark DL, Baylock J, Coe FL, Worcester EM. Sex differences in proximal and distal nephron function contribute to the mechanism of idiopathic hypercalcuria in calcium stone formers. Am J Physiol Regul Integr Comp Physiol 2015; 309:R85-92. [PMID: 25947170 DOI: 10.1152/ajpregu.00071.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 04/30/2015] [Indexed: 11/22/2022]
Abstract
Idiopathic hypercalciuria (IH) is a common familial trait among patients with calcium nephrolithiasis. Previously, we have demonstrated that hypercalciuria is primarily due to reduced renal proximal and distal tubule calcium reabsorption. Here, using measurements of the clearances of sodium, calcium, and endogenous lithium taken from the General Clinical Research Center, we test the hypothesis that patterns of segmental nephron tubule calcium reabsorption differ between the sexes in IH and normal subjects. When the sexes are compared, we reconfirm the reduced proximal and distal calcium reabsorption. In IH women, distal nephron calcium reabsorption is decreased compared to normal women. In IH men, proximal tubule calcium reabsorption falls significantly, with a more modest reduction in distal calcium reabsorption compared to normal men. Additionally, we demonstrate that male IH patients have lower systolic blood pressures than normal males. We conclude that women and men differ in the way they produce the hypercalciuria of IH, with females reducing distal reabsorption and males primarily reducing proximal tubule function.
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Affiliation(s)
- Benjamin Ko
- Department of Medicine, University of Chicago School of Medicine, Chicago, Illinois;
| | - Kristin Bergsland
- Department of Medicine, University of Chicago School of Medicine, Chicago, Illinois
| | - Daniel L Gillen
- Department of Statistics, University of California, Irvine, California; and
| | - Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Daniel L Clark
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jaime Baylock
- Department of Medicine, University of Chicago School of Medicine, Chicago, Illinois
| | - Fredric L Coe
- Department of Medicine, University of Chicago School of Medicine, Chicago, Illinois
| | - Elaine M Worcester
- Department of Medicine, University of Chicago School of Medicine, Chicago, Illinois
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Bhojani N, Paonessa JE, Hameed TA, Worcester EM, Evan AP, Coe FL, Borofsky MS, Lingeman JE. Nephrocalcinosis in Calcium Stone Formers Who Do Not have Systemic Disease. J Urol 2015; 194:1308-12. [PMID: 25988516 DOI: 10.1016/j.juro.2015.05.074] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/12/2015] [Indexed: 11/19/2022]
Abstract
PURPOSE Nephrocalcinosis is commonly present in primary hyperparathyroidism, distal renal tubular acidosis and medullary sponge kidney disease. To our knowledge it has not been studied in patients with calcium phosphate stones who do not have systemic disease. MATERIALS AND METHODS We studied patients undergoing percutaneous nephrolithotomy who had calcium phosphate or calcium oxalate stones and did not have hyperparathyroidism, distal renal tubular acidosis or medullary sponge kidney disease. On postoperative day 1 all patients underwent noncontrast computerized tomography. If there were no residual calcifications, the patient was categorized as not having nephrocalcinosis. If there were residual calcifications, the patient underwent secondary percutaneous nephrolithotomy. If the calcifications were found to be stones, the patient was categorized as not having nephrocalcinosis. If the calcifications were not stones, the patient was categorized as having nephrocalcinosis. Patients were grouped based on the type of stones that formed, including hydroxyapatite, brushite and idiopathic calcium oxalate. The extent of nephrocalcinosis was quantified as 0--absent nephrocalcinosis to 3--extensive nephrocalcinosis. Patients with residual calcifications on postoperative day 1 noncontrast computerized tomography who did not undergo secondary percutaneous nephrolithotomy were excluded from analysis. The presence or absence of nephrocalcinosis was correlated with metabolic studies. RESULTS A total of 67 patients were studied, including 14 with hydroxyapatite, 19 with brushite and 34 with idiopathic calcium oxalate calculi. Nephrocalcinosis was present in 10 of 14 (71.4%), 11 of 19 (57.9%) and 6 of 34 patients (17.6%) in the hydroxyapatite, brushite and idiopathic calcium oxalate groups, respectively (chi-square p = 0.01). The mean extent of nephrocalcinosis per group was 1.98, 1.32 and 0.18 for hydroxyapatite, brushite and idiopathic calcium oxalate, respectively (p ≤0.001). The presence of nephrocalcinosis positively correlated with urine calcium excretion (mean ± SD 287.39 ± 112.49 vs 223.68 ± 100.67 mg per day, p = 0.03). CONCLUSIONS Patients without systemic disease who form hydroxyapatite and brushite stones commonly have coexistent nephrocalcinosis. Nephrocalcinosis can occur in calcium oxalate stone formers but the quantity and frequency of nephrocalcinosis in this group are dramatically less.
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Affiliation(s)
- Naeem Bhojani
- Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Jessica E Paonessa
- Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Tariq A Hameed
- Department of Radiology, Indiana University School of Medicine, Indianapolis, Indiana
| | | | - Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Fredric L Coe
- Department of Nephrology, University of Chicago, Chicago, Illinois
| | - Michael S Borofsky
- Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana
| | - James E Lingeman
- Department of Urology, Indiana University School of Medicine, Indianapolis, Indiana.
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Evan AP, Coe FL, Connors BA, Handa RK, Lingeman JE, Worcester EM. Mechanism by which shock wave lithotripsy can promote formation of human calcium phosphate stones. Am J Physiol Renal Physiol 2015; 308:F938-49. [PMID: 25656372 PMCID: PMC4398833 DOI: 10.1152/ajprenal.00655.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 01/29/2015] [Indexed: 11/22/2022] Open
Abstract
Human stone calcium phosphate (CaP) content correlates with higher urine CaP supersaturation (SS) and urine pH as well as with the number of shock wave lithotripsy (SWL) treatments. SWL does damage medullary collecting ducts and vasa recta, sites for urine pH regulation. We tested the hypothesis that SWL raises urine pH and therefore Cap SS, resulting in CaP nucleation and tubular plugging. The left kidney (T) of nine farm pigs was treated with SWL, and metabolic studies were performed using bilateral ureteral catheters for up to 70 days post-SWL. Some animals were given an NH4Cl load to sort out effects on urine pH of CD injury vs. increased HCO3 (-) delivery. Histopathological studies were performed at the end of the functional studies. The mean pH of the T kidneys exceeded that of the control (C) kidneys by 0.18 units in 14 experiments on 9 pigs. Increased HCO3 (-) delivery to CD is at least partly responsible for the pH difference because NH4Cl acidosis abolished it. The T kidneys excreted more Na, K, HCO3 (-), water, Ca, Mg, and Cl than C kidneys. A single nephron site that could produce losses of all of these is the thick ascending limb. Extensive injury was noted in medullary thick ascending limbs and collecting ducts. Linear bands showing nephron loss and fibrosis were found in the cortex and extended into the medulla. Thus SWL produces tubule cell injury easily observed histopathologically that leads to functional disturbances across a wide range of electrolyte metabolism including higher than control urine pH.
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Affiliation(s)
- Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana; International Kidney Stone Institute, Methodist Hospital, Indianapolis, Indiana; and
| | - Fredric L Coe
- Nephrology Section, University of Chicago, Chicago, Illinois
| | - Bret A Connors
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Rajash K Handa
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - James E Lingeman
- International Kidney Stone Institute, Methodist Hospital, Indianapolis, Indiana; and
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Ennis JL, Worcester EM, Coe FL, Sprague SM. Current recommended 25-hydroxyvitamin D targets for chronic kidney disease management may be too low. J Nephrol 2015; 29:63-70. [PMID: 25736620 DOI: 10.1007/s40620-015-0186-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 02/24/2015] [Indexed: 11/28/2022]
Abstract
OBJECTIVE It is uncertain whether increasing 25-hydroxyvitamin D (25-D) levels in chronic kidney disease (CKD) patients above those recommended by current guidelines result in progressive amelioration of secondary hyperparathyroidism. Our objective was to identify a potential therapeutic 25-D target which optimally lowers plasma parathyroid hormone (PTH) without producing excessive hypercalcemia or hyperphosphatemia in CKD. METHODS We performed a cross-sectional analysis of 14,289 unselected stage 1-5 CKD patients from US primary care and nephrology practices utilizing a laboratory-based CKD clinical decision support service between September 2008 and May 2012. Estimated glomerular filtration rate (eGFR), plasma PTH, and serum 25-D, calcium, and phosphorus results were analyzed. RESULTS In CKD stages 3-5, progressively higher 25-D pentiles contained progressively lower mean PTH levels. Regression analysis of log PTH on 25-D was significant in all CKD stages with no evidence of a decreasing effect of 25-D to lower PTH until 25-D levels of 42-48 ng/ml. Progressively higher 25-D concentrations were not associated with increased rates of hypercalcemia or hyperphosphatemia. CONCLUSIONS We found evidence for an optimal level of 25-D above which suppression of PTH progressively diminishes. This level is more than twice that currently recommended for the general population. We found no association between these higher 25-D levels and hyperphosphatemia or hypercalcemia. Additional prospective trials seem appropriate to test the idea that 25-D levels around 40-50 ng/ml could be a safe and effective treatment target for secondary hyperparathyroidism in CKD.
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Affiliation(s)
- Jennifer L Ennis
- Litholink® Corporation, 2250 W. Campbell Park Drive, Chicago, IL, 60612, USA.
| | - Elaine M Worcester
- Section of Nephrology, Department of Medicine, University of Chicago, Chicago, IL, USA
| | - Fredric L Coe
- Section of Nephrology, Department of Medicine, University of Chicago, Chicago, IL, USA
| | - Stuart M Sprague
- Division of Nephrology and Hypertension, NorthShore University HealthSystem, Evanston, IL, USA
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Evan AP, Worcester EM, Williams JC, Sommer AJ, Lingeman JE, Phillips CL, Coe FL. Biopsy proven medullary sponge kidney: clinical findings, histopathology, and role of osteogenesis in stone and plaque formation. Anat Rec (Hoboken) 2015; 298:865-77. [PMID: 25615853 DOI: 10.1002/ar.23105] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 08/25/2014] [Accepted: 11/12/2014] [Indexed: 11/11/2022]
Abstract
Medullary sponge kidney (MSK) is associated with recurrent stone formation, but the clinical phenotype is unclear because patients with other disorders may be incorrectly labeled MSK. We studied 12 patients with histologic findings pathognomonic of MSK. All patients had an endoscopically recognizable pattern of papillary malformation, which may be segmental or diffuse. Affected papillae are enlarged and billowy, due to markedly enlarged inner medullary collecting ducts (IMCD), which contain small, mobile ductal stones. Patients had frequent dilation of Bellini ducts, with occasional mineral plugs. Stones may form over white (Randall's) plaque, but most renal pelvic stones are not attached, and have a similar morphology as ductal stones, which are a mixture of calcium oxalate and apatite. Patients had no abnormalities of urinary acidification or acid excretion; the most frequent metabolic abnormality was idiopathic hypercalciuria. Although both Runx2 and Osterix are expressed in papillae of MSK patients, no mineral deposition was seen at the sites of gene expression, arguing against a role of these genes in this process. Similar studies in idiopathic calcium stone formers showed no expression of these genes at sites of Randall's plaque. The most likely mechanism for stone formation in MSK appears to be crystallization due to urinary stasis in dilated IMCD with subsequent passage of ductal stones into the renal pelvis where they may serve as nuclei for stone formation.
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Affiliation(s)
- Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
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Evan AP, Worcester EM, Coe FL, Williams J, Lingeman JE. Mechanisms of human kidney stone formation. Urolithiasis 2014; 43 Suppl 1:19-32. [PMID: 25108546 DOI: 10.1007/s00240-014-0701-0] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 07/23/2014] [Indexed: 01/08/2023]
Abstract
The precise mechanisms of kidney stone formation and growth are not completely known, even though human stone disease appears to be one of the oldest diseases known to medicine. With the advent of the new digital endoscope and detailed renal physiological studies performed on well phenotyped stone formers, substantial advances have been made in our knowledge of the pathogenesis of the most common type of stone former, the idiopathic calcium oxalate stone former as well as nine other stone forming groups. The observations from our group on human stone formers and those of others on model systems have suggested four entirely different pathways for kidney stone formation. Calcium oxalate stone growth over sites of Randall's plaque appear to be the primary mode of stone formation for those patients with hypercalciuria. Overgrowths off the ends of Bellini duct plugs have been noted in most stone phenotypes, do they result in a clinical stone? Micro-lith formation does occur within the lumens of dilated inner medullary collecting ducts of cystinuric stone formers and appear to be confined to this space. Lastly, cystinuric stone formers also have numerous small, oval, smooth yellow appearing calyceal stones suggestive of formation in free solution. The scientific basis for each of these four modes of stone formation are reviewed and used to explore novel research opportunities.
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Affiliation(s)
- Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS 5055, Indianapolis, IN, 46220, USA,
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Abstract
Micro-computed tomographic imaging (micro-CT) provides unprecedented information on stone structure and mineral composition. High-resolution micro-CT even allows visualization of the lumens of tubule and/or vessels within Randall's plaque, on stones or in papillary biopsies, thus giving a non-destructive way to study these sites of stone adhesion. This paper also shows an example of a stone growing on a different anchoring mechanism: a mineral plug within the lumen of a Bellini duct (BD plug). Micro-CT shows striking structural differences between stones that have grown on Randall's plaque and those that have grown on BD plugs. Thus, Randall's plaque can be distinguished by micro-CT, and this non-destructive method shows great promise in helping to elucidate the different mechanisms by which small stones are retained in the kidney during the development of nephrolithiasis.
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Affiliation(s)
- James C Williams
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive MS 5055Y, Indianapolis, IN, 46202-5120, USA,
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Evan AP, Lingeman JE, Worcester EM, Sommer AJ, Phillips CL, Williams JC, Coe FL. Contrasting histopathology and crystal deposits in kidneys of idiopathic stone formers who produce hydroxy apatite, brushite, or calcium oxalate stones. Anat Rec (Hoboken) 2014; 297:731-48. [PMID: 24478243 DOI: 10.1002/ar.22881] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 12/16/2013] [Indexed: 12/11/2022]
Abstract
Our previous work has shown that stone formers who form calcium phosphate (CaP) stones that contain any brushite (BRSF) have a distinctive renal histopathology and surgical anatomy when compared with idiopathic calcium oxalate stone formers (ICSF). Here we report on another group of idiopathic CaP stone formers, those forming stone containing primarily hydroxyapatite, in order to clarify in what ways their pathology differs from BRSF and ICSF. Eleven hydroxyapatite stone formers (HASF) (2 males, 9 females) were studied using intra-operative digital photography and biopsy of papillary and cortical regions to measure tissue changes associated with stone formation. Our main finding is that HASF and BRSF differ significantly from each other and that both differ greatly from ICSF. Both BRSF and ICSF patients have significant levels of Randall's plaque compared with HASF. Intra-tubular deposit number is greater in HASF than BRSF and nonexistent in ICSF while deposit size is smaller in HASF than BRSF. Cortical pathology is distinctly greater in BRSF than HASF. Four attached stones were observed in HASF, three in 25 BRSF and 5-10 per ICSF patient. HASF and BRSF differ clinically in that both have higher average urine pH, supersaturation of CaP, and calcium excretion than ICSF. Our work suggests that HASF and BRSF are two distinct and separate diseases and both differ greatly from ICSF.
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Affiliation(s)
- Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana; Department of Urology, International Kidney Stone Institute, Methodist Hospital, Indianapolis, Indiana
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Worcester EM, Evan AP, Coe FL, Lingeman JE, Krambeck A, Sommers A, Phillips CL, Milliner D. A test of the hypothesis that oxalate secretion produces proximal tubule crystallization in primary hyperoxaluria type I. Am J Physiol Renal Physiol 2013; 305:F1574-84. [PMID: 24089413 DOI: 10.1152/ajprenal.00382.2013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The sequence of events by which primary hyperoxaluria type 1 (PH1) causes renal failure is unclear. We hypothesize that proximal tubule (PT) is vulnerable because oxalate secretion raises calcium oxalate (CaOx) supersaturation (SS) there, leading to crystal formation and cellular injury. We studied cortical and papillary biopsies from two PH1 patients with preserved renal function, and seven native kidneys removed from four patients at the time of transplant, after short-term (2) or longer term (2) dialysis. In these patients, and another five PH1 patients without renal failure, we calculated oxalate secretion, and estimated PT CaOx SS. Plasma oxalate was elevated in all PH1 patients and inverse to creatinine clearance. Renal secretion of oxalate was present in all PH1 but rare in controls. PT CaOx SS was >1 in all nonpyridoxine-responsive PH1 before transplant and most marked in patients who developed end stage renal disease (ESRD). PT from PH1 with preserved renal function had birefringent crystals, confirming the presence of CaOx SS, but had no evidence of cortical inflammation or scarring by histopathology or hyaluronan staining. PH1 with short ESRD showed CaOx deposition and hyaluronan staining particularly at the corticomedullary junction in distal PT while cortical collecting ducts were spared. Longer ESRD showed widespread cortical CaOx, and in both groups papillary tissue had marked intratubular CaOx deposits and fibrosis. CaOx SS in PT causes CaOx crystal formation, and CaOx deposition in distal PT appears to be associated with ESRD. Minimizing PT CaOx SS may be important for preserving renal function in PH1.
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Affiliation(s)
- Elaine M Worcester
- Nephrology Section, MC5100, Univ. of Chicago, School of Medicine, 5841 South Maryland Ave., Chicago, IL 60637.
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Abstract
INTRODUCTION Kidney stones are a common problem worldwide with substantial morbidities and economic costs. Medical therapy reduces stone recurrence significantly. Much progress has been made in the last several decades in improving therapy of stone disease. AREAS COVERED This review discusses i) the effect of medical expulsive therapy on spontaneous stone passage, ii) pharmacotherapy in the prevention of stone recurrence and iii) future directions in the treatment of kidney stone disease. EXPERT OPINION Fluid intake to promote urine volume of at least 2.5 L each day is essential to prevent stone formation. Dietary recommendations should be adjusted based on individual metabolic abnormalities. Properly dosed thiazide treatment is the standard therapy for calcium stone formers with idiopathic hypercalciuria. Potassium alkali therapy is considered for hypocitraturia, but caution should be taken to prevent potential risk of calcium phosphate stone formation. For absorptive hyperoxaluria, low oxalate diet and increased dietary calcium intake are recommended. Pyridoxine has been shown effective in some cases of primary hyperoxaluria type I. Allopurinol is used in calcium oxalate stone formers with hyperuricosuria. Treatment of cystine stones remains challenging. Tiopronin can be used if urinary alkalinization and adequate fluid intake are insufficient. For struvite stones, complete surgical removal coupled with appropriate antibiotic therapy is necessary.
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Affiliation(s)
- Hongshi Xu
- University of Chicago Medical Center, University of Chicago Pritzker School of Medicine, Chicago, IL, USA
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Worcester EM, Bergsland KJ, Gillen DL, Coe FL. Evidence for increased renal tubule and parathyroid gland sensitivity to serum calcium in human idiopathic hypercalciuria. Am J Physiol Renal Physiol 2013; 305:F853-60. [PMID: 23863465 DOI: 10.1152/ajprenal.00124.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Patients with idiopathic hypercalciuria (IH) have decreased renal calcium reabsorption, most marked in the postprandial state, but the mechanisms are unknown. We compared 29 subjects with IH and 17 normal subjects (N) each fed meals providing identical amounts of calcium. Urine and blood samples were collected fasting and after meals. Levels of three candidate signalers, serum calcium (SCa), insulin (I), and plasma parathyroid hormone (PTH), did not differ between IH and N either fasting or fed, but all changed with feeding, and the change in SCa was greater in IH than in N. Regression analysis of fractional excretion of calcium (FECa) was significant for PTH and SCa in IH but not N. With the use of multivariable analysis, Sca entered the model while PTH and I did not. To avoid internal correlation we decomposed FECa into its independent terms: adjusted urine calcium (UCa) and UFCa molarity. Analyses using adjusted Uca and unadjusted Uca parallel those using FECa, showing a dominant effect of SCa with no effect of PTH or I. The effect of SCa may be mediated via vitamin D receptor-stimulated increased abundance of basolateral Ca receptor, which is supported by the fact PTH levels also seem more responsive to serum Ca in IH than in N. Although our data support an effect of SCa on FECa and UCa, which is more marked in IH than in N, it can account for only a modest fraction of the meal effect, perhaps 10-20%, suggesting additional mediators are also responsible for the exaggerated postprandial hypercalciuria seen in IH.
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Affiliation(s)
- Elaine M Worcester
- Nephrology Section MC 5100, Univ. of Chicago Medicine, 5841 South Maryland Ave., Chicago, IL 60637.
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Bergsland KJ, Worcester EM, Coe FL. Role of proximal tubule in the hypocalciuric response to thiazide of patients with idiopathic hypercalciuria. Am J Physiol Renal Physiol 2013; 305:F592-9. [PMID: 23720347 DOI: 10.1152/ajprenal.00116.2013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The most common metabolic abnormality found in calcium (Ca) kidney stone formers is idiopathic hypercalciuria (IH). Using endogenous lithium (Li) clearance, we previously showed that in IH, there is decreased proximal tubule sodium absorption, and increased delivery of Ca into the distal nephron. Distal Ca reabsorption may facilitate the formation of Randall's plaque (RP) by washdown of excess Ca through the vasa recta toward the papillary tip. Elevated Ca excretion leads to increased urinary supersaturation (SS) with respect to calcium oxalate (CaOx) and calcium phosphate (CaP), providing the driving force for stone growth on RP. Thiazide (TZ) diuretics reduce Ca excretion and prevent stone recurrence, but the mechanism in humans is unknown. We studied the effect of chronic TZ administration on renal mineral handling in four male IH patients using a fixed three meal day in the General Clinical Research Center. Each subject was studied twice: once before treatment and once after 4-7 mo of daily chlorthalidone treatment. As expected, urine Ca fell with TZ, along with fraction of filtered Ca excreted. Fraction of filtered Li excreted also fell sharply with TZ, as did distal delivery of Ca. Unexpectedly, TZ lowered urine pH. Together with reduced urine Ca, this led to a marked fall in CaP SS, but not CaOx SS. Since CaOx stone formation begins with an initial CaP overlay on RP, by lowering urine pH and decreasing distal nephron Ca delivery, TZ might diminish stone risk both by reducing CaP SS, as well as slowing progression of RP.
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Affiliation(s)
- Kristin J Bergsland
- The Univ. of Chicago, Section of Nephrology/MC5100, 5841 S. Maryland Ave., Chicago, IL 60637.
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Bhojani N, Paonessa JE, Worcester EM, Evan AP, Coe FL, Lingeman JE. 2254 THE MAJORITY OF CALCIUM PHOSPHATE STONE FORMERS WITHOUT SYSTEMIC DISEASE HAVE NEPHROCALCINOSIS. J Urol 2013. [DOI: 10.1016/j.juro.2013.02.2163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Bergsland KJ, Zisman AL, Asplin JR, Worcester EM, Coe FL. Evidence for net renal tubule oxalate secretion in patients with calcium kidney stones. Am J Physiol Renal Physiol 2010; 300:F311-8. [PMID: 21123489 DOI: 10.1152/ajprenal.00411.2010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Little is known about the renal handling of oxalate in patients with idiopathic hypercalciuria (IH). To explore the role of tubular oxalate handling in IH and to evaluate whether differences exist between IH and normal controls, we studied 19 IH subjects, 8 normal subjects, and 2 bariatric stone formers (BSF) during a 1-day General Clinical Research Center protocol utilizing a low-oxalate diet. Urine and blood samples were collected at 30- to 60-min intervals while subjects were fasting and after they ate three meals providing known amounts of calcium, phosphorus, sodium, protein, oxalate, and calories. Plasma oxalate concentrations and oxalate-filtered loads were similar between patients (includes IH and BSF) and controls in both the fasting and fed states. Urinary oxalate excretion was significantly higher in patients vs. controls regardless of feeding state. Fractional excretion of oxalate (FEOx) was >1, suggesting tubular secretion of oxalate, in 6 of 19 IH and both BSF, compared with none of the controls (P < 0.00001). Adjusted for water extraction along the nephron, urine oxalate rose more rapidly among patients than normal subjects with increases in plasma oxalate. Our findings identify tubular secretion of oxalate as a key mediator of hyperoxaluria in calcium stone formers, potentially as a means of maintaining plasma oxalate in a tight range.
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Affiliation(s)
- Kristin J Bergsland
- Department of Medicine, Nephrology Section, The University of Chicago, Chicago, IL 60637, USA.
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Evan AP, Weinman EJ, Wu XR, Lingeman JE, Worcester EM, Coe FL. Comparison of the pathology of interstitial plaque in human ICSF stone patients to NHERF-1 and THP-null mice. ACTA ACUST UNITED AC 2010; 38:439-52. [PMID: 21063698 DOI: 10.1007/s00240-010-0330-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Accepted: 10/08/2010] [Indexed: 11/28/2022]
Abstract
Extensive evidence now supports the role of papillary interstitial deposits-Randall's plaques-in the formation of stones in the idiopathic, calcium oxalate stone former. These plaques begin as deposits of apatite in the basement membranes of the thin limbs of Henle's loop, but can grow to become extensive deposits beneath the epithelium covering the papillary surface. Erosion of this covering epithelium allows deposition of calcium oxalate onto this plaque material, and the transition of mineral type and organic material from plaque to stone has been investigated. The fraction of the papilla surface that is covered with Randall's plaque correlates with stone number in these patients, as well as with urine calcium excretion, and plaque coverage also correlates inversely with urine volume and pH. Two animal models--the NHERF-1 and THP-null mice--have been shown to develop sites of interstitial apatite plaque in the renal papilla. In these animal models, the sites of interstitial plaque in the inner medulla are similar to that found in human idiopathic calcium oxalate stone formers, except that the deposits in the mouse models are not localized solely to the basement membrane of the thin limbs of Henle's loop, as in humans. This may be due to the different morphology of the human versus mouse papillary region. Both mouse models appear to be important to characterize further in order to determine how well they mimic human kidney stone disease.
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Affiliation(s)
- Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS 5055S, Indianapolis, IN 46223, USA.
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Affiliation(s)
- Elaine M Worcester
- Nephrology Section, Department of Medicine, University of Chicago, Chicago, IL 60637, USA.
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Worcester EM, Coe FL. Evidence for altered renal tubule function in idiopathic calcium stone formers. ACTA ACUST UNITED AC 2010; 38:263-9. [PMID: 20632168 DOI: 10.1007/s00240-010-0299-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 06/30/2010] [Indexed: 11/30/2022]
Abstract
Patients who form calcium kidney stones often have metabolic disorders such as idiopathic hypercalciuria (IH) that reflect abnormalities in mineral handling in the kidney. Renal handling of calcium is altered by ingestion of nutrients such as carbohydrates, protein, and sodium, and patients with IH appear to be more sensitive to these stimuli. Studies using probes such as diuretics or lithium clearance have the ability to clarify which nephron segments are involved in the altered renal calcium transport with nutrient seen in IH. Studies in the genetic hypercalciuric rat demonstrate alterations in both proximal tubule and thick ascending limb calcium reabsorption. Similar studies in humans have begun to provide evidence about the corresponding abnormalities in stone formers with IH. A pattern of altered renal tubule transport in calcium stone formers is suggested by the frequency of such findings as decreased tubular maximal reabsorption of phosphate and abnormal urine acidification as well as hypercalciuria in such patients, not explained by monogenic transport abnormalities.
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Affiliation(s)
- Elaine M Worcester
- Nephrology Section/MC 5100, Department of Medicine, University of Chicago, 5841 South Maryland Avenue, Chicago, IL 60637, USA.
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Abstract
Data concerning nine forms of human stone disease, along with observations on normal people give new insights into formation of interstitial apatite plaque and intra-tubular crystal deposits. In general, across multiple disease states, one can reproduce the same relationships between plaque abundance as is seen among patients within individual disease states, so that the link between plaque and high urine calcium excretion, and low urine volume and pH seems increasingly secure. From this, one can propose a specific model of plaque formation, susceptible to experimental test. In many diseases, formation of inner medullary collecting duct and Bellini duct deposits is compatible with simple crystallization driven by urine supersaturations; this is expected in that these segments contain tubule fluid quite close in composition to final urine. But in ileostomy, small bowel disease and obesity bypass patients, crystals found in deposits are not those expected: apatite and urates in deposits, despite formation of highly acidic urine. Also, this discrepancy suggests the possibility of divergence between bulk urine pH and pH of focal collecting ducts, a new kind of possibility that is susceptible to experimental test.
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Affiliation(s)
- Fredric L Coe
- Renal Section MC5100, University of Chicago School of Medicine, 5841 South Maryland Avenue, Chicago, IL 60637, USA.
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Abstract
No single theory of pathogenesis can properly account for human kidney stones, they are too various and their formation is too complex for simple understanding. Using human tissue biopsies, intraoperative imaging and such physiology data from ten different stone forming groups, we have identified at least three pathways that lead to stones. The first pathway is overgrowth on interstitial apatite plaque as seen in idiopathic calcium oxalate stone formers, as well as stone formers with primary hyperparathyroidism, ileostomy, and small bowel resection, and in brushite stone formers. In the second pathway, there are crystal deposits in renal tubules that were seen in all stone forming groups except the idiopathic calcium oxalate stone formers. The third pathway is free solution crystallization. Clear examples of this pathway are those patient groups with cystinuria or hyperoxaluria associated with bypass surgery for obesity. Although the final products may be very similar, the ways of creation are so different that in attempting to create animal and cell models of the processes one needs to be careful that the details of the human condition are included.
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Affiliation(s)
- Fredric L Coe
- Department of Medicine, University of Chicago, Nephrology Section/MC 5100, 5841 South Maryland Avenue, Chicago, IL, 60637, USA.
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Evan AP, Lingeman JE, Coe FL, Bledsoe SB, Sommer AJ, Williams JC, Krambeck AE, Worcester EM. Intra-tubular deposits, urine and stone composition are divergent in patients with ileostomy. Kidney Int 2009; 76:1081-8. [PMID: 19710630 DOI: 10.1038/ki.2009.321] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Patients with ileostomy typically have recurrent renal stones and produce scanty, acidic, sodium-poor urine because of abnormally large enteric losses of water and sodium bicarbonate. Here we used a combination of intra-operative digital photography and biopsy of the renal papilla and cortex to measure changes associated with stone formation in seven patients with ileostomy. Papillary deformity was present in four patients and was associated with decreased estimated glomerular filtration rates. All patients had interstitial apatite plaque, as predicted from their generally acid, low-volume urine. Two patients had stones attached to plaque; however, all patients had crystal deposits that plugged the ducts of Bellini and inner medullary collecting ducts (IMCDs). Despite acid urine, all crystal deposits contained apatite, and five patients had deposits of sodium and ammonium acid urates. Stones were either uric acid or calcium oxalate as predicted by supersaturation, however, there was a general lack of supersaturation for calcium phosphate as brushite, sodium, or ammonium acid urate because of the overall low urine pH. This suggests that local tubular pH exceeds that of bulk urine. Despite low urine pH, patients with an ileostomy resemble those with obesity bypass, in whom IMCD apatite crystal plugs are found. They are, however, unlike these bypass patients in having interstitial apatite plaque. IMCD plugging with sodium and ammonium acid urate has not been found previously and appears to correlate with formation of uric acid stones.
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Affiliation(s)
- Andrew P Evan
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana 46223, USA.
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Bergsland KJ, Coe FL, Gillen DL, Worcester EM. A test of the hypothesis that the collecting duct calcium-sensing receptor limits rise of urine calcium molarity in hypercalciuric calcium kidney stone formers. Am J Physiol Renal Physiol 2009; 297:F1017-23. [PMID: 19640901 DOI: 10.1152/ajprenal.00223.2009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The process of kidney stone formation depends on an imbalance between excretion of water and insoluble stone-forming salts, leading to high concentrations that supersaturate urine and inner medullary collecting duct (IMCD) fluid. For common calcium-containing stones, a critical mechanism that has been proposed for integrating water and calcium salt excretions is activation of the cell surface calcium-sensing receptor (CaSR) on the apical membranes of IMCD cells. High deliveries of calcium into the IMCD would be predicted to activate CaSR, leading to reduced membrane abundance of aquaporin-2, thereby limiting water conservation and protecting against stone formation. We have tested this hypothesis in 16 idiopathic hypercalciuric calcium stone formers and 14 matched normal men and women in the General Clinical Research Center. Subjects were fed identical diets; we collected 14 urine samples at 1-h intervals during a single study day, and one sample overnight. Hypercalciuria did not increase urine volume, so urine calcium molarity and supersaturation with respect to calcium oxalate and calcium phosphate rose proportionately to calcium excretion. Thus CaSR modulation of urine volume via IMCD CaSR activation does not appear to be an important mechanism of protection against stone formation. The overnight period, one of maximal water conservation, was a time of maximal stone risk and perhaps a target of specific clinical intervention.
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Affiliation(s)
- Kristin J Bergsland
- Sect. of Nephrology/MC5100, The Univ. of Chicago, 5841 S. Maryland Ave., Chicago, IL 60637, USA.
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Worcester EM, Coe FL. Does Idiopathic Hypercalciuria Trigger Calcium-Sensing Receptor–Mediated Protection from Urinary Supersaturation? J Am Soc Nephrol 2009; 20:1657-9. [DOI: 10.1681/asn.2009060580] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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Miller NL, Williams JC, Evan AP, Bledsoe SB, Coe FL, Worcester EM, Munch LC, Handa SE, Lingeman JE. In idiopathic calcium oxalate stone-formers, unattached stones show evidence of having originated as attached stones on Randall's plaque. BJU Int 2009; 105:242-5. [PMID: 19549258 DOI: 10.1111/j.1464-410x.2009.08637.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To analyse the structure and composition of unattached stones in idiopathic calcium oxalate (CaOx) stone-formers (ICSF) and compare them to attached stones from the same cohort, to investigate whether there is more than one pathogenic mechanism for stone formation in ICSF. PATIENTS AND METHODS ICSF undergoing percutaneous nephrolithotomy or ureteroscopy for the treatment of nephrolithiasis gave consent to participate in this study. All accessible renal papillae were endoscopically imaged using a digital endoscope. All stones were removed and determined by the operating surgeon to be attached or unattached to the underlying papilla. Micro-computed tomography (micro-CT), which provides three-dimensional analysis of entire stones, was used to compare the structure and composition of attached and unattached stones. RESULTS Of 115 stones collected from nine patients (12 renal units), only 25 stones were found not to be attached to renal papillae. Of these 25 stones, four were lost and 12 showed definite morphological evidence of having been attached to tissue, probably having been displaced from papillae during access. For the remaining nine stones, micro-CT analysis showed at least one internal region of calcium phosphate within each of these unattached CaOx stones, i.e. the internal structure of the unattached stones is consistent with their having originated attached to Randall's plaque, and then having become detached but retained in the kidney, with new layers of CaOx eventually covering the original attachment site. CONCLUSIONS; Micro-CT analysis supports the hypothesis that in ICSF, both attached and unattached stones occur as a result of a common pathogenic mechanism, i.e. in this type of stone former, CaOx stones, even those not showing morphology that betrays attachment, all originate attached to interstitial plaque on the renal papilla.
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Affiliation(s)
- Nicole L Miller
- Department of Urologic Surgery, Vanderbilt University School of Medicine, Nashville, TN 37232,, USA.
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