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Engeßer J, Albert PG, Scheuch M, Loth N, Stracke S. The Calcimimetic R568 Reduces Vascular Smooth Muscle Cell Calcification in Vitro Via ERK 1/2 Phosphorylation. Int J Nephrol 2025; 2025:2492846. [PMID: 40135106 PMCID: PMC11936526 DOI: 10.1155/ijne/2492846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2024] [Accepted: 02/26/2025] [Indexed: 03/27/2025] Open
Abstract
Background: Vascular calcification (VC) is a common complication of chronic kidney disease, ultimately leading to high morbidity and cardiovascular mortality. In this study, we investigated the effects of the calcimimetic R568 in an in vitro model of human vascular smooth muscle cell (VSMC) calcification. Methods: Human VSMCs were cultured under elevated calcium (2.4 mmol/L) and phosphate (2.7 mmol/L) concentrations. Calcification was analyzed using von Kossa staining and colorimetric calcium measurement. Intracellular signaling was examined via Western blot, and apoptosis was assessed by the TUNEL assay. Results: Treatment with R568 significantly reduced VC over the 9-day treatment period. R568 treatment led to increased phosphorylation of extracellular signal-regulated kinase (ERK 1/2) compared to the control group. Calcimimetic treatment was also associated with a reduction in apoptosis. Blocking ERK 1/2 phosphorylation completely abolished the inhibitory effects of R568 on VC. Conclusion: Our study provides new insights into the mechanism of action of calcimimetics during VC and highlights the importance of ERK 1/2 signaling in this process.
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Affiliation(s)
- Jonas Engeßer
- Department of Internal Medicine A, Division of Nephrology, University Medicine Greifswald, Greifswald, Germany
- Department of Internal Medicine A, Nephrology Research-Laboratory, University Medicine Greifswald, Greifswald, Germany
| | - Philipp Gregor Albert
- Department of Internal Medicine A, Nephrology Research-Laboratory, University Medicine Greifswald, Greifswald, Germany
| | - Matthias Scheuch
- Department of Internal Medicine A, Nephrology Research-Laboratory, University Medicine Greifswald, Greifswald, Germany
| | - Norina Loth
- Department of Internal Medicine A, Nephrology Research-Laboratory, University Medicine Greifswald, Greifswald, Germany
| | - Sylvia Stracke
- Department of Internal Medicine A, Division of Nephrology, University Medicine Greifswald, Greifswald, Germany
- Department of Internal Medicine A, Nephrology Research-Laboratory, University Medicine Greifswald, Greifswald, Germany
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Sin HK, Lo KY, Lo MW, Chan SF, Lo KC, Wong YY, Ho LY, Kwok WT, Chan KC, Kwong JM, Mak SK, Wong PN. Bisphosphonate therapy for persistent hyperparathyroidism after kidney transplantation-A case report. Nephrology (Carlton) 2025; 30:e14415. [PMID: 39654330 DOI: 10.1111/nep.14415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 03/20/2024] [Accepted: 11/17/2024] [Indexed: 12/28/2024]
Abstract
Post-transplant hyperparathyroidism (PT-HPT) is common in kidney transplant recipients (KTRs) and can cause nephrocalcinosis and graft dysfunction. Cinacalcet is commonly used for treating PT-HPT but may induce calciuria and exacerbate nephrocalcinosis. The concurrent use of bisphosphonates with cinacalcet to prevent this complication has not been reported. We report a case of PT-HPT-associated graft dysfunction. The patient had ESRD due to IgAN. She had been on continuous ambulatory peritoneal dialysis (CAPD) for 7 years before undergoing kidney transplantation (KT). Pre-KT intact parathyroid hormone (iPTH) was 101 pmol/L, alkaline phosphatase (ALP) 205 IU/L, Ca 2.40 mmol/L and PO4 2.2 mmol/L. There was immediate graft function after KT and the existence of persistent hyperparathyroidism (Cr 72 μmol/L, eGFR > 60 mL/min/1.73 m2, Ca 2.85 mmol/L, PO4 0.6 mmol/L, ALP 315 IU/L, iPTH 16.4 pmol/L). Progressive renal impairment ensued over the next 10 months (Cr 146 μmol/L, eGFR 34 mL/min/1.73 m2, Ca 2.77 mmol/L, PO4 0.9 mmol/L, ALP 142 IU/L, iPTH 24.4 pmol/L). Graft biopsy at 10 months post-KT revealed widespread tubular calcifications and no evidence of rejection. Intravenous pamidronate 60 mg was given quarterly for 3 doses in addition to cinacalcet therapy. ALP decreased from 147 to 81 IU/L despite refractory PT-HPT and renal function improved. Total parathyroidectomy was performed 1 month after the last pamidronate dose. Renal function remained stable for up to 4 years post-KT (Cr 151 μmol/L, eGFR 33 mL/min/1.73 m2, Ca 2.19 mmol/L, PO4 1.3 mmol/L, ALP 70 IU/L, iPTH < 0.1 pmol/L). Our case report highlights the therapeutic potential of pamidronate in addition to cinacalcet in the management of PT-HPT-associated nephrocalcinosis.
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Affiliation(s)
| | | | | | | | | | | | - Lo-Yi Ho
- Kwong Wah Hospital, Kowloon, Hong Kong
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The use of cinacalcet after pediatric renal transplantation: an international CERTAIN Registry analysis. Pediatr Nephrol 2020; 35:1707-1718. [PMID: 32367310 DOI: 10.1007/s00467-020-04558-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 03/18/2020] [Accepted: 03/27/2020] [Indexed: 10/24/2022]
Abstract
BACKGROUND Secondary hyperparathyroidism (SHPT) may persist after renal transplantation (RTx), inducing hypophosphatemia and hypercalcemia that precludes the use of vitamin D analogs. The calcimimetic cinacalcet improved plasma calcium and parathyroid hormone (PTH) levels in randomized controlled trials in adults after RTx, but pediatric data are scarce. METHODS In this retrospective study, we analyzed 20 pediatric patients from the Cooperative European Paediatric Renal TransplAnt Initiative (CERTAIN) Registry who received cinacalcet after RTx. The results are presented as median and interquartile range (25th-75th percentile). RESULTS At 13.7 (11.0-16.5) years of age, 20 pediatric patients received a renal allograft. Cinacalcet was introduced at 0.4 (0.3-2.7) years post-transplant at an estimated glomerular filtration rate (eGFR) of 50 (34-66) mL/min/1.73 m2, plasma calcium of 2.58 (2.39-2.71) mmol/L, age-standardized (z score) phosphate of - 1.7 (- 2.7-- 0.4), and PTH of 136 (95-236) ng/L. The starting dose of cinacalcet was 0.5 (0.3-0.8) mg/kg per day, with a maximum dose of 1.1 (0.5-1.3) mg/kg per day. With a follow-up of 3.0 (1.5-3.6) years on cinacalcet therapy, eGFR remained stable; PTH levels decreased to 66 (56-124) ng/L at the last follow-up (p = 0.015). One patient displayed hypocalcemia (1.8 mmol/L). Cinacalcet was withdrawn in three patients (hypocalcemia, parathyroidectomy, incompliance). Nephrocalcinosis of the graft was not reported. CONCLUSIONS This pilot study suggests that cinacalcet as off-label therapy for SHPT after pediatric RTx is efficacious in controlling post-transplant SHPT with acceptable tolerability. Continuing cinacalcet even with normal PTH can lead to dangerous life-threatening hypocalcemia. Therefore, at each subsequent visit, the need to continue cinacalcet must be assessed.
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Hamano T. Vitamin D and renal outcome: the fourth outcome of CKD-MBD? Oshima Award Address 2015. Clin Exp Nephrol 2018; 22:249-256. [PMID: 29270765 PMCID: PMC5838134 DOI: 10.1007/s10157-017-1517-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 10/11/2017] [Indexed: 12/29/2022]
Abstract
Bone fracture, cardiovascular events, and mortality are three outcomes of chronic kidney disease-mineral and bone disorder (CKD-MBD), and the umbrella concept originally described for dialysis patients. The reported association of serum phosphorus or fibroblast growth factor 23 (FGF23) levels with renal outcome suggests that the fourth relevant outcome of CKD-MBD in predialysis patients is renal outcome. We found that proteinuria of 2+ or greater with a dipstick test was associated with low vitamin D status due to urinary loss of 25-hydroxyvitamin D (25D). Moreover, active vitamin D or its analogues decrease proteinuria. Given our finding that maxacalcitol does not repress renin, the reduction of proteinuria by this agent is likely due to direct upregulation of the nephrin and podocin in podocytes. Moreover, this agent downregulates the mesenchymal marker desmin in podocytes and blocks transforming growth factor-beta autoinduction, leading to attenuation of renal fibrosis in a unilateral ureteral obstructive (UUO) model. These facts are reminiscent of the suppression of epithelial-mesenchymal transition (EMT) by vitamin D. EMT blockage may explain our finding that vitamin D prescription in renal transplant recipients is associated with a lower incidence of cancer. We also reported that low vitamin D status and high FGF23 levels predict a worse renal outcome. However, administration of massive doses of 25D exacerbates renal fibrosis in UUO kidneys in 1alpha-hydroxylase knockout mice. Moreover, FGF23 inhibits 1alpha-hydroxylase in proximal tubules and monocytes. Taken together, local 1,25(OH)2D in the kidney tissue but not 25D seems to protect the kidney.
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Affiliation(s)
- Takayuki Hamano
- Department of Comprehensive Kidney Disease Research (CKDR), Osaka University Graduate School of Medicine, D11, 2-2 Yamadaoka, Suita, Osaka, Japan.
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Dulfer RR, Franssen GJH, Hesselink DA, Hoorn EJ, van Eijck CHJ, van Ginhoven TM. Systematic review of surgical and medical treatment for tertiary hyperparathyroidism. Br J Surg 2017; 104:804-813. [PMID: 28518414 DOI: 10.1002/bjs.10554] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 11/23/2016] [Accepted: 03/01/2017] [Indexed: 12/31/2022]
Abstract
BACKGROUND A significant proportion of patients with chronic kidney disease and secondary hyperparathyroidism (HPT) remain hyperparathyroid after kidney transplantation, a state known as tertiary HPT. Without treatment, tertiary HPT can lead to diminished kidney allograft and patient survival. Parathyroidectomy was commonly performed to treat tertiary HPT until the introduction of the calcimimetic drug, cinacalcet. It is not known whether surgery or medical treatment is superior for tertiary HPT. METHODS A systematic review was performed and medical literature databases were searched for studies on the treatment of tertiary HPT that were published after the approval of cinacalcet. RESULTS A total of 1669 articles were identified, of which 47 were included in the review. Following subtotal and total parathyroidectomy, initial cure rates were 98·7 and 100 per cent respectively, but in 7·6 and 4 per cent of patients tertiary HPT recurred. After treatment with cinacalcet, 80·8 per cent of the patients achieved normocalcaemia. Owing to side-effects, 6·4 per cent of patients discontinued cinacalcet treatment. The literature regarding graft function and survival is limited; however, renal graft survival after surgical treatment appears comparable to that obtained with cinacalcet therapy. CONCLUSION Side-effects and complications of both treatment modalities were mild and occurred in a minority of patients. Surgical treatment for tertiary HPT has higher cure rates than medical therapy.
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Affiliation(s)
- R R Dulfer
- Department of Surgery, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | - G J H Franssen
- Department of Surgery, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | - D A Hesselink
- Department of Nephrology and Kidney Transplantation, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | - E J Hoorn
- Department of Nephrology and Kidney Transplantation, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | - C H J van Eijck
- Department of Surgery, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands
| | - T M van Ginhoven
- Department of Surgery, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands
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Long-term clinical practice experience with cinacalcet for treatment of hypercalcemic hyperparathyroidism after kidney transplantation. BIOMED RESEARCH INTERNATIONAL 2015; 2015:292654. [PMID: 25861621 PMCID: PMC4377458 DOI: 10.1155/2015/292654] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 02/09/2015] [Indexed: 12/11/2022]
Abstract
Within this prospective, open-label, self-controlled study, we evaluated the long-term effects of the calcimimetic cinacalcet on calcium and phosphate homeostasis in 44 kidney transplant recipients (KTRs) with hypercalcemic hyperparathyroidism by comparing biochemical parameters of mineral metabolism between pre- and posttreatment periods. Results are described as mean differences (95% CIs) between pre- and posttreatment medians that summarize all repeated measurements of a parameter of interest between the date of initial hypercalcemia and cinacalcet initiation (median of 1.6 (IQR: 0.6-3.8) years) and up to four years after treatment start, respectively. Cinacalcet was initiated after 1.8 (0.8-4.7) years posttransplant and maintained for 6.2 (3.9-7.6) years. It significantly decreased total serum calcium (-0.30 (-0.34 to -0.26) mmol/L, P < 0.001) and parathyroid hormone levels (-79 (-103 to -55) pg/mL, P < 0.001). Serum levels of inorganic phosphate (Pi) and renal tubular reabsorption of phosphate to glomerular filtration rate (TmP/GFR) increased simultaneously (Pi: 0.19 (0.15-0.23) mmol/L, P < 0.001, TmP/GFR: 0.20 (0.16-0.23) mmol/L, P < 0.001). In summary, cinacalcet effectively controlled hypercalcemic hyperparathyroidism in KTRs in the long-term and increased low Pi levels without causing hyperphosphatemia, pointing towards a novel indication for the use of cinacalcet in KTRs.
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Evenepoel P, Cooper K, Holdaas H, Messa P, Mourad G, Olgaard K, Rutkowski B, Schaefer H, Deng H, Torregrosa JV, Wuthrich RP, Yue S. A randomized study evaluating cinacalcet to treat hypercalcemia in renal transplant recipients with persistent hyperparathyroidism. Am J Transplant 2014; 14:2545-55. [PMID: 25225081 DOI: 10.1111/ajt.12911] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 05/15/2014] [Accepted: 05/18/2014] [Indexed: 01/25/2023]
Abstract
Persistent hyperparathyroidism (HPT) after kidney transplantation (KTx) is associated with hypercalcemia, hypophosphatemia and abnormally high levels of parathyroid hormone (PTH). In this randomized trial, cinacalcet was compared to placebo for the treatment of hypercalcemia in adult patients with persistent HPT after KTx. Subjects were randomized 1:1 to cinacalcet or placebo with randomization stratified by baseline corrected total serum calcium levels (≤11.2 mg/dL [2.80 mmol/L] or >11.2 mg/dL [2.80 mmol/L]). The primary end point was achievement of a mean corrected total serum calcium value<10.2 mg/dL (2.55 mmol/L) during the efficacy period. The two key secondary end points were percent change in bone mineral density (BMD) at the femoral neck and absolute change in phosphorus; 78.9% cinacalcet- versus 3.5% placebo-treated subjects achieved the primary end point with a difference of 75.4% (95% confidence interval [CI]: 63.8, 87.1), p<0.001. There was no statistical difference in the percent change in BMD at the femoral neck between cinacalcet and placebo groups, p=0.266. The difference in the change in phosphorus between the two arms was 0.45 mg/dL (95% CI: 0.26, 0.64), p<0.001 (nominal). No new safety signals were detected. In conclusion, hypercalcemia and hypophosphatemia were effectively corrected after treatment with cinacalcet in patients with persistent HPT after KTx.
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Affiliation(s)
- P Evenepoel
- Department of Nephrology and Renal Transplantation, University Hospitals Leuven, Leuven, Belgium
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Kuczera P, Adamczak M, Wiecek A. Cinacalcet treatment decreases plasma fibroblast growth factor 23 concentration in haemodialysed patients with chronic kidney disease and secondary hyperparathyroidism. Clin Endocrinol (Oxf) 2014; 80:607-12. [PMID: 24111496 DOI: 10.1111/cen.12326] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 05/07/2013] [Accepted: 09/11/2013] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Recent clinical studies suggest that fibroblast growth factor 23 (FGF23) is important in the pathogenesis of calcium-phosphate abnormalities in patients with chronic kidney disease and that increased plasma FGF23 concentration is a cardiovascular risk factor in these patients. The aim of this prospective, single-arm, open-label clinical study was to assess the influence of 6-month cinacalcet treatment on plasma FGF23 concentration in haemodialysed patients with secondary hyperparathyroidism (sHPT). DESIGN, PATIENTS AND MEASUREMENTS In 58 haemodialysed patients with sHPT (parathormone PTH > 300 ng/l), serum PTH, FGF23, calcium and phosphate concentrations were assessed before the first dose of cinacalcet and after 3 and 6 months of treatment. RESULTS Serum PTH concentration decreased significantly after 3 and 6 months of treatment, and the mean serum calcium and phosphate concentrations remained stable during the treatment period. Plasma FGF23 concentration (geometric mean with 95% confidence index) decreased after 3 and 6 months of treatment from 354 (261-481) ng/l to 295 (204-428) ng/l; P = 0·099 and to 183 (117-285) ng/l; P = 0·015, respectively. FGF23 concentration decreased in 52% of patients. In multivariate regression analysis, plasma FGF23 concentration changes were explained by the changes in serum phosphate, but not by serum PTH or calcium changes or by the dose of cinacalcet. CONCLUSIONS 1. Cinacalcet treatment decreases plasma FGF23 concentration in haemodialysed patients with secondary hyperparathyroidism. 2. The decrease in plasma FGF23 concentration seems to be related to the decrease in serum phosphate concentration.
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Affiliation(s)
- Piotr Kuczera
- Department of Nephrology, Endocrinology and Metabolic Diseases, Medical University of Silesia, Katowice, Poland
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Cinacalcet for the treatment of hyperparathyroidism in kidney transplant recipients: a systematic review and meta-analysis. Transplantation 2013; 94:1041-8. [PMID: 23069843 DOI: 10.1097/tp.0b013e31826c3968] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Hyperparathyroidism is present in up to 50% of transplant recipients 1 year after transplant, often despite good graft function. Posttransplant patients frequently have hypercalcemia-associated hyperparathyroidism, limiting the role of vitamin D analogues and sometimes requiring parathyroidectomy. Multiple observational studies have investigated treatment of posttransplant hyperparathyroidism with the calcimimetic agent cinacalcet. METHODS We performed a systematic review and meta-analysis of prospective and retrospective studies from 2004 through January 26, 2012, using MEDLINE. We identified studies evaluating treatment with cinacalcet in renal transplant recipients with hyperparathyroidism. We performed random effects meta-analysis to determine changes in calcium, phosphorus, parathyroid hormone, and serum creatinine. RESULTS Twenty-one studies with 411 kidney transplant recipients treated with cinacalcet for hyperparathyroidism met inclusion criteria. Patients were treated for 3 to 24 months. By meta-analysis, calcium decreased by 1.14 mg/dL (95% confidence interval, -1.00 to -1.28), phosphorus increased by 0.46 mg/dL (95% confidence interval, 0.28-0.64), parathyroid hormone decreased by 102 pg/mL (95% confidence interval, -69 to -134), and there was no significant change in creatinine (0.02 mg/dL decrease; 95% confidence interval, -0.09 to 0.06). Cinacalcet resulted in hypocalcemia in seven patients. The most common side effect was gastrointestinal intolerance. CONCLUSIONS From nonrandomized studies, cinacalcet appears to be safe and effective for the treatment of posttransplant hyperparathyroidism. Larger observational studies and randomized controlled trials, performed over longer follow-up times and looking at clinical outcomes, are needed to corroborate these findings.
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Alshayeb HM, Josephson MA, Sprague SM. CKD-mineral and bone disorder management in kidney transplant recipients. Am J Kidney Dis 2012; 61:310-25. [PMID: 23102732 DOI: 10.1053/j.ajkd.2012.07.022] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 07/09/2012] [Indexed: 12/11/2022]
Abstract
Kidney transplantation, the most effective treatment for the metabolic abnormalities of chronic kidney disease (CKD), only partially corrects CKD-mineral and bone disorders. Posttransplantation bone disease, one of the major complications of kidney transplantation, is characterized by accelerated loss of bone mineral density and increased risk of fractures and osteonecrosis. The pathogenesis of posttransplantation bone disease is multifactorial and includes the persistent manifestations of pretransplantation CKD-mineral and bone disorder, peritransplantation changes in the fibroblast growth factor 23-parathyroid hormone-vitamin D axis, metabolic perturbations such as persistent hypophosphatemia and hypercalcemia, and the effects of immunosuppressive therapies. Posttransplantation fractures occur more commonly at peripheral than central sites. Although there is significant loss of bone density after transplantation, the evidence linking posttransplantation bone loss and subsequent fracture risk is circumstantial. Presently, there are no prospective clinical trials that define the optimal therapy for posttransplantation bone disease. Combined pharmacologic therapy that targets multiple components of the disordered pathways has been used. Although bisphosphonate or calcitriol therapy can preserve bone mineral density after transplantation, there is no evidence that these agents decrease fracture risk. Moreover, bisphosphonates pose potential risks for adynamic bone disease.
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Affiliation(s)
- Hala M Alshayeb
- Department of Medicine, Section of Nephrology, University of Chicago, Chicago, IL, USA
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Zhang R, Chouhan KK. Metabolic bone diseases in kidney transplant recipients. World J Nephrol 2012; 1:127-33. [PMID: 24175250 PMCID: PMC3782213 DOI: 10.5527/wjn.v1.i5.127] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2011] [Revised: 06/01/2012] [Accepted: 09/25/2012] [Indexed: 02/06/2023] Open
Abstract
Metabolic bone disease after kidney transplantation has a complex pathophysiology and heterogeneous histology. Pre-existing renal osteodystrophy may not resolve completely, but continue or evolve into a different osteodystrophy. Rapid bone loss immediately after transplant can persist, at a lower rate, for years to come. These greatly increase the risk of bone fracture and vertebral collapse. Each patient may have multiple risk factors of bone loss, such as steroids usage, hypogonadism, persistent hyperparathyroidism (HPT), poor allograft function, metabolic acidosis, hypophosphatemia, vitamin D deficiency, aging, immobility and chronic disease. Clinical management requires a comprehensive approach to address the underlying and ongoing disease processes. Successful prevention of bone loss has been shown with vitamin D, bisphosphonates, calcitonin as well as treatment of hypogonadism and HPT. Novel approach to restore the normal bone remodeling and improve the bone quality may be needed in order to effectively decrease bone fracture rate in kidney transplant recipients.
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Affiliation(s)
- Rubin Zhang
- Rubin Zhang, Kanwaljit K Chouhan, Section of Nephrology, Department of Medicine, Tulane University School of Medicine, New Orleans, LA 70112, United States
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Felsenfeld AJ, Levine BS. Approach to Treatment of Hypophosphatemia. Am J Kidney Dis 2012; 60:655-61. [DOI: 10.1053/j.ajkd.2012.03.024] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 06/19/2012] [Indexed: 12/25/2022]
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Tomida K, Hamano T, Ichimaru N, Fujii N, Matsui I, Nonomura N, Tsubakihara Y, Rakugi H, Takahara S, Isaka Y. Dialysis vintage and parathyroid hormone level, not fibroblast growth factor-23, determines chronic-phase phosphate wasting after renal transplantation. Bone 2012; 51:729-36. [PMID: 22796419 DOI: 10.1016/j.bone.2012.06.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 06/07/2012] [Accepted: 06/27/2012] [Indexed: 12/11/2022]
Abstract
PURPOSE Fibroblast growth factor 23 (FGF23), rather than parathyroid hormone (PTH), has been shown to be the major factor behind hypophosphatemia in the early period after renal transplantation. However, it is not clear whether phosphate wasting persists in the chronic phase. Purpose of our study is to elucidate whether FGF23 can also explain phosphate wasting, if any, in the chronic phase. METHODS In this cross-sectional observational study, we enrolled 247 recipients who had received a graft more than 1 year prior to this study. We compared the phosphate metabolism of recipients and predialysis chronic kidney disease (CKD) patients who are matched on age and estimated glomerular filtration rate (eGFR). We also investigated the determinants of tubular reabsorption of phosphate normalized for glomerular filtration rate (TmP/GFR), as an index of renal threshold for phosphate. RESULTS Recipients had a median dialysis vintage of 27.0 months and eGFR 41.2 mL/min/1.73 m(2). Whereas hypophosphatemia (<2.4 mg/dL) was observed in 6.1% of the recipients, 55.2% had TmP/GFR lower than 2.4 mg/dL. Recipients showed significantly lower TmP/GFR in all CKD stages than their predialysis counterparts, indicating that phosphate wasting persists in the chronic phase. Compared to predialysis patients, the recipients in stages 2T and 3T showed lower phosphate and higher intact PTH levels, despite a higher percentage being active vitamin D users. However, in stage 4T, phosphate retention masked relative hypophosphatemia. FGF23 was higher in the recipients across all CKD stages, but adjustment for vitamin D prescription revealed that transplantation had no effect on FGF23. Multiple regression analysis in the recipients showed significant negative associations of intact PTH and dialysis vintage with TmP/GFR. CONCLUSIONS Renal phosphate wasting persists in the chronic-phase renal transplantation recipients even with normophosphatemia. Persistent hyperparathyroidism and longer dialysis vintage, not FGF23, was associated with renal phosphate wasting in the chronic phase. Such an impact on phosphate metabolism of the factors determined in dialysis period could be called as "uremic memory". This novel finding in the chronic phase is in sharp contrast to the previous finding in the early phase that FGF23 levels are determinants of phosphate wasting.
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Affiliation(s)
- Kodo Tomida
- Department of Kidney Disease and Hypertension, Osaka General Medical Center, 3-1-56 Bandai-higashi, Osaka, 558-8558, Japan
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Effect of cinacalcet on renal electrolyte handling and systemic arterial blood pressure in kidney transplant patients with persistent hyperparathyroidism. Transplantation 2011; 92:883-9. [PMID: 21876476 DOI: 10.1097/tp.0b013e31822d87e8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND The calcimimetic cinacalcet has recently been increasingly used for persistent hyperparathyroidism after renal transplantation. The present study investigated the short-term effects of cinacalcet on urinary electrolyte concentration and arterial blood pressure in kidney transplant patients with persistent hyperparathyroidism. METHODS In a prospective controlled single-center cross-over study, we examined 10 stable kidney transplant patients (mean estimated glomerular filtration rate 51±10 mL/min/1.73 m(2)) who received cinacalcet daily for persistent hyperparathyroidism. Urine specimens were collected at baseline and every 2 hr for a total study period of 6 hr after ingestion of 30 mg cinacalcet and without cinacalcet. Intact parathyroid hormone was determined at baseline and 2 hr later. Using ambulatory blood pressure measurement, arterial blood pressure was determined every 15 min. RESULTS Intact parathyroid hormone was significantly reduced with cinacalcet as compared with controls (-37±27.7% vs. -9.6±10.3%, P=0.009). With cinacalcet, urinary calcium and magnesium concentration were increased (P=0.042 and P=0.007, respectively) and differed significantly as compared with the control phase without cinacalcet. After 4 hr, an increased urinary sodium concentration was also found compared with the control phase (P=0.039). Systolic blood pressure was reduced with cinacalcet (P<0.001) and differed significantly from control phase (-13.7±9.9 mm Hg vs. -3.2±5.2 mm Hg after 2 hr, P=0.009; -18.1±10.8 mm Hg vs. -1.9±5.2 mm Hg after 4 hr, P=0.001). CONCLUSIONS In the short term, cinacalcet increases the urinary concentration of calcium, magnesium, and sodium. The observed antihypertensive effect might be beneficial in patients with a high cardiovascular risk after kidney transplantation.
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Guzzo I, Di Zazzo G, Laurenzi C, Ravà L, Giannone G, Picca S, Dello Strologo L. Parathyroid hormone levels in long-term renal transplant children and adolescents. Pediatr Nephrol 2011; 26:2051-7. [PMID: 21556715 DOI: 10.1007/s00467-011-1896-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Revised: 03/14/2011] [Accepted: 03/15/2011] [Indexed: 12/26/2022]
Abstract
Secondary hyperparathyroidism is a common complication of chronic renal failure. Kidney transplantation corrects renal insufficiency and most metabolic abnormalities but hyperparathyroidism persists in 50% of children after transplantation. The aim of this study was to investigate parathyroid hormone (PTH) course and potential risk factors for hyperparathyroidism in children after renal transplant. We collected data from 145 transplanted children (mean follow-up 4.7 years). Intact PTH level (iPTH) rapidly decreased in the first 6 months post-transplant and continued to decline in the following years. iPTH was above the normal range in 69.1% of the patients at the time of transplant and in 47% 1 year later, this improvement continuing thereafter. Hypercalcemia was present in 20.3% of the patients before transplant and in 6.3 and 4.1% of patients 6 months and 1 year after transplant, respectively. Hypophosphatemia was present in 5.5% of the patients at 6 months, and 45.5% of the patients needed phosphorus supplements during the first 6 months after transplant. Multivariate analysis indicated pre-transplant hyperparathyroidism, dialysis duration, creatinine clearance and hypophosphatemia as predictors of persistent hyperparathyroidism. In kidney transplanted children, serum iPTH normalized in the long term in the majority of cases. Thus, parathyroidectomy should be reserved for selected patients.
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Affiliation(s)
- Isabella Guzzo
- Nephrology and Urology Department, Bambino Gesù Children's Hospital and Research Institute (IRCCS), Piazza S. Onofrio 4, 00165 Rome, Italy.
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Damasiewicz MJ, Toussaint ND, Polkinghorne KR. Fibroblast growth factor 23 in chronic kidney disease: New insights and clinical implications. Nephrology (Carlton) 2011; 16:261-8. [PMID: 21265930 DOI: 10.1111/j.1440-1797.2011.01443.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Fibroblast growth factor 23 (FGF-23) is a recently discovered regulator of phosphate and mineral metabolism. Its main physiological function is the enhancement of renal phosphate excretion. FGF-23 levels are inversely related to renal function and in patients with chronic kidney disease (CKD) elevation in FGF-23 precedes the rise of serum phosphate. Studies have demonstrated an important role for FGF-23 in the development of secondary hyperparathyroidism through an effect on parathyroid hormone and calcitriol. In cross-sectional studies FGF-23 has been associated with surrogate markers of cardiovascular disease such as endothelial dysfunction and arterial stiffness. FGF-23 has also been associated with both progression of CKD and mortality in dialysis patients. The discovery of FGF-23 has provided a profound new insight into bone and mineral metabolism, and it may become an important biomarker and therapeutic target in CKD.
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Affiliation(s)
- Matthew J Damasiewicz
- Department of Nephrology, Monash Medical Centre, Monash University, Clayton, Victoria, Australia.
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17
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Copley JB, Wüthrich RP. Therapeutic management of post-kidney transplant hyperparathyroidism. Clin Transplant 2011; 25:24-39. [PMID: 20572835 DOI: 10.1111/j.1399-0012.2010.01287.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Left uncontrolled, persistent post-kidney transplant hyperparathyroidism (HPT) may lead to or exacerbate pre-existing bone and cardiovascular disease. Parathyroidectomy has long been the primary treatment option for long-term uncontrolled HPT in post-kidney transplant patients. However, patients with contraindications for surgery and parathyroidectomy-associated complications, including graft loss, highlight the need for other approaches. Conventional medical therapies have limited impact on serum calcium (Ca) and parathyroid hormone (PTH) levels. Bisphosphonates and calcitonin, used to spare bone loss, and phosphorus supplementation, to correct hypophosphatemia, do not directly regulate PTH or Ca. Although vitamin D supplementation can reduce PTH, it is often contraindicated because of hypercalcemia. Studies of the calcimimetic cinacalcet in patients with post-kidney transplant HPT suggest that it can rapidly reduce serum PTH and Ca concentrations while increasing serum phosphorus concentrations toward the normal range. Although the clearest application for cinacalcet is the non-surgical treatment of hypercalcemic patients with persistent HPT, current indications for other transplant patients are as yet uncertain. Further studies are needed to determine the utility of cinacalcet in patients with spontaneous resolution of HPT or low bone turnover. This review discusses the pathophysiology of post-kidney transplant HPT, associated complications, and current options for clinical management.
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18
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Alon US. Clinical practice. Fibroblast growth factor (FGF)23: a new hormone. Eur J Pediatr 2011; 170:545-54. [PMID: 21193927 DOI: 10.1007/s00431-010-1382-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 12/14/2010] [Indexed: 12/13/2022]
Abstract
Until a decade ago, two main hormones were recognized as directly affecting phosphate homeostasis and, with that, bone metabolism: parathyroid hormone and 1,25(OH)(2) vitamin D (calcitriol). It was only a decade ago that the third major player hormone was found, linking gut, bone, and kidney. The physiologic role of fibrinogen growth factor (FGF)23 is to maintain serum phosphate concentration within a narrow range. Secreted from osteocytes, it modulates kidney handling of phosphate reabsorption and calcitriol production. Genetic and acquired abnormalities in FGF23 structure and metabolism cause conditions of either hyper-FGF23-manifested by hypophosphatemia, low serum calcitriol, and rickets/osteomalacia-or hypo-FGF23, expressed by hyperphosphatemia, high serum calcitriol, and extra-skeletal calcifications. In patients with chronic renal failure, FGF23 levels increase as kidney functions deteriorate and are under investigation to learn if the hormone actually participates in the pathophysiology of the deranged bone and mineral metabolism typical for these patients and, if so, whether it might serve as a therapeutic target. This review addresses the physiology and pathophysiology of FGF23 and its clinical applications.
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Affiliation(s)
- Uri S Alon
- Bone and Mineral Disorders Clinic, Section of Pediatric Nephrology, Children's Mercy Hospitals and Clinics, University of Missouri at Kansas City School of Medicine, 2401 Gillham Road, Kansas City, MO 64108, USA.
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Riella LV, Rennke HG, Grafals M, Chandraker A. Hypophosphatemia in kidney transplant recipients: report of acute phosphate nephropathy as a complication of therapy. Am J Kidney Dis 2011; 57:641-5. [PMID: 21333424 DOI: 10.1053/j.ajkd.2010.11.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 11/26/2010] [Indexed: 12/11/2022]
Abstract
Hypophosphatemia is a common complication after kidney transplant, affecting >90% of patients. However, no specific recommendations for phosphate repletion exist for transplant recipients. We report a case of a 70-year-old highly sensitized woman with end-stage renal disease caused by diabetic nephropathy who underwent deceased donor kidney transplant. Four weeks later, she was noted to have hypophosphatemia with undetectable serum phosphate levels, and she reported mild diarrhea. She was started on oral phosphate supplementation. On a routine visit 2 weeks later, she was found to have an acute increase in serum creatinine level and kidney biopsy was performed. We discuss the causes, management, and complications of hypophosphatemia in kidney transplant.
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Affiliation(s)
- Leonardo V Riella
- Transplantation Research Center, Renal Division, Brigham & Women's Hospital, Children's Hospital Boston, Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA
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20
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Abstract
Hypophosphatemia caused by inappropriate urinary phosphate wasting is a frequent metabolic complication of the early period following kidney transplantation. Although previously considered to be caused by tertiary hyperparathyroidism, recent evidence suggests a primary role for persistently elevated circulating levels of the phosphorus-regulating hormone, FGF23. In the setting of a healthy renal allograft, markedly increased FGF23 levels from the dialysis period induce renal phosphate wasting and inhibition of calcitriol production, which contribute to hypophosphatemia. While such tertiary FGF23 excess and resultant hypophosphatemia typically abates within the first few weeks to months post-transplant, some recipients manifest persistent renal phosphate wasting. Furthermore, increased FGF23 levels have been associated with increased risk of kidney disease progression, cardiovascular disease, and death outside of the transplant setting. Whether tertiary FGF23 excess is associated with adverse transplant outcomes is unknown. In this article, we review the physiology of FGF23, summarize its relationship with hypophosphatemia after kidney transplantation, and speculate on its potential impact on long-term outcomes of renal allograft recipients.
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Affiliation(s)
- Wacharee Seeherunvong
- Division of Pediatric Nephrology, Department of Pediatrics, University of Miami Miller School of Medicine, Miami, Florida
| | - Myles Wolf
- Division of Nephrology and Hypertension, Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida
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21
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Seikrit C, Mühlfeld A, Groene HJ, Floege J. Renal allograft failure in a hyperparathyroid patient following initiation of a calcimimetic. Nat Rev Nephrol 2010; 7:237-41. [DOI: 10.1038/nrneph.2010.169] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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22
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Morales E, Gutierrez E, Andres A. Treatment with calcimimetics in kidney transplantation. Transplant Rev (Orlando) 2010; 24:79-88. [DOI: 10.1016/j.trre.2010.01.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Accepted: 01/18/2010] [Indexed: 11/26/2022]
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Abstract
Fibroblast growth factor (FGF)-23 is a recently discovered regulator of calcium-phosphate metabolism. Whereas other known FGFs mainly act in a paracrine manner, FGF-23 has significant systemic effects. Together with its cofactor Klotho, FGF-23 enhances renal phosphate excretion in order to maintain serum phosphate levels within the normal range. In patients with chronic kidney disease (CKD), FGF-23 levels rise in parallel with declining renal function long before a significant increase in serum phosphate concentration can be detected. However, in cross-sectional studies increased FGF-23 levels in patients with CKD were found to be associated not only with therapy-resistant secondary hyperparathyroidism but were also independently related to myocardial hypertrophy and endothelial dysfunction after adjustment for traditional markers of calcium-phosphate metabolism. Finally, in prospective studies high serum FGF-23 concentrations predicted faster disease progression in CKD patients not on dialysis, and increased mortality in patients receiving maintenance hemodialysis. FGF-23 may therefore prove to be an important therapeutic target in the management of CKD.
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Affiliation(s)
- Sarah Seiler
- Department of Internal Medicine IV-Renal and Hypertensive Disease, Saarland University Medical Centre, Homburg/Saar, Germany
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Current world literature. Curr Opin Endocrinol Diabetes Obes 2009; 16:470-80. [PMID: 19858911 DOI: 10.1097/med.0b013e3283339a46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
In light of greatly improved long-term patient and graft survival after renal transplantation, improving other clinical outcomes such as risk of fracture and cardiovascular disease is of paramount importance. After renal transplantation, a large percentage of patients lose bone. This loss of bone results from a combination of factors that include pre-existing renal osteodystrophy, immunosuppressive therapy, and the effects of chronically reduced renal function after transplantation. In addition to low bone volume, histological abnormalities include decreased bone turnover and defective mineralization. Low bone volume and low bone turnover were recently shown to be associated with cardiovascular calcifications, highlighting specific challenges for medical therapy and the need to prevent low bone turnover in the pretransplant patient. This Review discusses changes in bone histology and mineral metabolism that are associated with renal transplantation and the effects of these changes on clinical outcomes such as fractures and cardiovascular calcifications. Therapeutic modalities are evaluated based on our understanding of bone histology.
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Cannata-Andía JB, Fernández-Martín JL. Mineral metabolism: Should cinacalcet be used in patients who are not on dialysis? Nat Rev Nephrol 2009; 5:307-8. [PMID: 19474823 DOI: 10.1038/nrneph.2009.54] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cinacalcet is an effective treatment for secondary hyperparathyroidism in patients on dialysis. Until now, no randomized, placebo-controlled, long-term trial has tested this drug in individuals with chronic kidney disease who are not receiving dialysis.
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Evolution of Secondary Hyperparathyroidism After Kidney Transplantation in Patients Receiving Cinacalcet on Dialysis. Transplant Proc 2009; 41:2396-8. [DOI: 10.1016/j.transproceed.2009.06.073] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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28
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Kalantar-Zadeh K, Kovesdy CP. Is it worth correcting hyperparathyroidism if hyperphosphatemia and hypocalcemia worsen? A cinacalcet story. Am J Kidney Dis 2009; 53:183-8. [PMID: 19166796 DOI: 10.1053/j.ajkd.2008.12.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 12/04/2008] [Indexed: 01/17/2023]
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