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Bover J, Trinidad P, Jara A, Soler-Majoral J, Martín-Malo A, Torres A, Frazão J, Ureña P, Dusso A, Arana C, Graterol F, Romero-González G, Troya M, Samaniego D, D'Marco L, Valdivielso JM, Fernández E, Arenas MD, Torregrosa V, Navarro-González JF, Lloret MJ, Ballarín JA, Bosch RJ, Górriz JL, de Francisco A, Gutiérrez O, Ara J, Felsenfeld A, Canalejo A, Almadén Y. Silver jubilee: 25 years of the first demonstration of the direct effect of phosphate on the parathyroid cell. Nefrologia 2022; 42:645-655. [PMID: 36925324 DOI: 10.1016/j.nefroe.2023.02.008] [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: 12/27/2021] [Accepted: 12/30/2021] [Indexed: 06/18/2023] Open
Abstract
Although phosphorus is an essential element for life, it is not found in nature in its native state but rather combined in the form of inorganic phosphates (PO43-), with tightly regulated plasma levels that are associated with deleterious effects and mortality when these are out of bounds. The growing interest in the accumulation of PO43- in human pathophysiology originated in its attributed role in the pathogenesis of secondary hyperparathyroidism (SHPT) in chronic kidney disease. In this article, we review the mechanisms by which this effect was justified and we commemorate the important contribution of a Spanish group led by Dr. M. Rodríguez, just 25 years ago, when they first demonstrated the direct effect of PO43- on the regulation of the synthesis and secretion of parathyroid hormone by maintaining the structural integrity of the parathyroid glands in their original experimental model. In addition to demonstrating the importance of arachidonic acid (AA) and the phospholipase A2-AA pathway as a mediator of parathyroid gland response, these findings were predecessors of the recent description of the important role of PO43- on the activity of the calcium sensor-receptor, and also fueled various lines of research on the importance of PO43- overload not only for the pathophysiology of SHPT but also in its systemic pathogenic role.
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Affiliation(s)
- Jordi Bover
- Servicio de Nefrología, Hospital Universitario Germans Trias i Pujol, RICORS, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Universitat Autònoma de Barcelona, Badalona (Barcelona), Spain.
| | - Pedro Trinidad
- Departamento de Nefrología, HECMN siglo XXI, IMSS, Ciudad de México, México
| | - Aquiles Jara
- Departamento de Nefrología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Jordi Soler-Majoral
- Servicio de Nefrología, Hospital Universitario Germans Trias i Pujol, RICORS, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Universitat Autònoma de Barcelona, Badalona (Barcelona), Spain
| | - Alejandro Martín-Malo
- Unidad de Gestión Clinica Nefrología, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Universitario Reina Sofía, Universidad de Córdoba, España. Red Nacional de Investigación en Nefrología (REDinREN), Instituto de Salud Carlos III, Spain
| | - Armando Torres
- Servicio de Nefrología, Hospital Universitario de Canarias, Instituto de Tecnologías Biomédicas, Universidad de La Laguna, Tenerife, Spain
| | - João Frazão
- Department of Nephrology, Centro Hospitalar Universitário São João, Institute for Innovation and Health Research (I3S), Institute of Biomedical Engineering (INEB), Nephrology and Infectious Diseases Research Group, University of Porto, Porto, Portugal
| | - Pablo Ureña
- AURA Nord Saint Ouen Dialysis Service. Saint Ouen, France and Service d'Explorations Fonctionnelles Rénales, Hôpital Necker, Université Paris V, René Descartes, Paris, France
| | - Adriana Dusso
- Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, St Louis, MO, USA
| | - Carolt Arana
- Departamento de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España
| | - Fredzzia Graterol
- Servicio de Nefrología, Hospital Universitario Germans Trias i Pujol, RICORS, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Universitat Autònoma de Barcelona, Badalona (Barcelona), Spain
| | - Gregorio Romero-González
- Servicio de Nefrología, Hospital Universitario Germans Trias i Pujol, RICORS, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Universitat Autònoma de Barcelona, Badalona (Barcelona), Spain
| | - Maribel Troya
- Servicio de Nefrología, Hospital Universitario Germans Trias i Pujol, RICORS, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Universitat Autònoma de Barcelona, Badalona (Barcelona), Spain
| | - Diana Samaniego
- Servicio de Nefrología, Hospital Universitario Germans Trias i Pujol, RICORS, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Universitat Autònoma de Barcelona, Badalona (Barcelona), Spain
| | - Luis D'Marco
- CEU Cardenal Herrera University, Valencia, Spain
| | - José Manuel Valdivielso
- Vascular and Renal Translational Research Group, Biomedical Research Institute, IRBLLEIDA, Lleida, España. Red Nacional de Investigación en Nefrología (REDinREN, RETIC), Instituto de Salud Carlos III, Spain
| | - Elvira Fernández
- Vascular and Renal Translational Research Group, Biomedical Research Institute, IRBLLEIDA, Lleida, España. Red Nacional de Investigación en Nefrología (REDinREN, RETIC), Instituto de Salud Carlos III, Spain; Grupo de Investigación Traslacional Vascular y Renal, Fundación Renal Jaume Arnó, Lleida, Spain
| | | | - Vicente Torregrosa
- Departamento de Nefrología y Trasplante Renal, Hospital Clínic, Barcelona, España
| | - Juan F Navarro-González
- Unidad de Investigación y Servicio de Nefrología, Hospital Universitario Nuestra Señora de la Candelaria, Instituto Universitario de Tecnologías Biomédicas, Universidad de la Laguna, Santa Cruz de Tenerife, España. Red Nacional de Investigación en Nefrología (REDinREN, RICORS), Instituto de Salud Carlos III, Spain
| | - María Jesús Lloret
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, Barcelona, Spain
| | - J A Ballarín
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, Barcelona, Spain
| | - Ricardo J Bosch
- Unidad de Fisiología, Departamento de Biología de Sistemas, Facultad de Medicina, Universidad de Alcalá, Alcalá de Henares, Madrid, Spain
| | - José L Górriz
- Servicio de Nefrología, Hospital Clínico Universitario, INCLIVA, Universidad de Valencia, Valencia, Spain
| | | | - Orlando Gutiérrez
- Division of Nephrology, Department of Medicine, Universidad de Alabama en Birmingham, Birmingham USA
| | - Jordi Ara
- Servicio de Nefrología, Hospital Universitario Germans Trias i Pujol, RICORS, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol (IGTP), Universitat Autònoma de Barcelona, Badalona (Barcelona), Spain
| | - Arnold Felsenfeld
- Department of Medicine, Veterans Affairs Greater Los Angeles Healthcare System and David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Antonio Canalejo
- Departamento de Ciencias Integradas/Centro de Investigación RENSMA, Facultad de Ciencias Experimentales, Universidad de Huelva. Huelva, Spain
| | - Yolanda Almadén
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Universitario Reina Sofía, Universidad de Córdoba, Córdoba, Spain
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Zhang X, Xu W, Huang T, Huang J, Zhang C, Zhang Y, Xie X, Xu M. The value of clinical-ultrasonographic feature model to predict the severity of secondary hyperparathyroidism. Ren Fail 2022; 44:146-154. [PMID: 35164637 PMCID: PMC8856024 DOI: 10.1080/0886022x.2022.2027784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Objectives To analyze conventional ultrasound (CUS) and contrast-enhanced ultrasound (CEUS) features in patients with secondary hyperparathyroidism (SHPT) and to evaluate the clinical-ultrasonographic feature based model for predicting the severity of SHPT. Methods From February 2016 to March 2021, a total of 59 patients (age 51.3 ± 11.7 years, seCr 797.8 ± 431.7 μmol/L, iPTH 1535.1 ± 1063.9 ng/L) with SHPT (including 181 parathyroid glands (PTGs)) without the history of intact parathyroid hormone (iPTH)-reducing drugs using were enrolled. The patients were divided into the mild SHPT group (mSHPT, iPTH <800 ng/L) and the severe SHPT group (sSHPT, iPTH ≥ 800 ng/L) according to the serum iPTH level. The clinical test data of patients were collected and CUS and CEUS examinations were performed for every patient. Multivariable logistic regression model according to clinical-ultrasonographic features was adopted to establish a nomogram. We performed K-fold cross-validation on this nomogram model and nomogram performance was determined by its discrimination, calibration, and clinical usefulness. Results There were 19 patients in the mSHPT group and 40 patients in the sSHPT group. Multivariable logistic regression indicated serum calcium, serum phosphorus and total volume of PTGs were independent predictors related with serum iPTH level. Even though CEUS score of wash-in and wash-out were showed related to severity of SHPT in univariate logistic regression analysis, they were not predictors of SHPT severity (p = 0.539, 0.474 respectively). The nomogram developed by clinical and ultrasonographic features showed good calibration and discrimination. The accuracy and the area under the curve (AUC), positive predictive value (PPV), negative predictive value (NPV) and accuracy of this model were 0.888, 92.5%, 63.2% and 83.1%, respectively. When applied to internal validation, the score revealed good discrimination with stratified fivefold cross-validation in the cohort (mean AUC = 0.833). Conclusions The clinical-ultrasonographic features model has good performance for predicting the severity of SHPT.
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Affiliation(s)
- Xiaoer Zhang
- Department of Medical Ultrasonics, The First Affiliated Hospital, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, Guangzhou, China
| | - Wenxin Xu
- Department of Medical Ultrasonics, The First Affiliated Hospital, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, Guangzhou, China
| | - Tongyi Huang
- Department of Medical Ultrasonics, The First Affiliated Hospital, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, Guangzhou, China
| | - Jingzhi Huang
- Department of Medical Ultrasonics, The First Affiliated Hospital, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, Guangzhou, China
| | - Chunyang Zhang
- Department of Medical Ultrasonics, The First Affiliated Hospital, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, Guangzhou, China
| | - Yutong Zhang
- Department of Medical Ultrasonics, The First Affiliated Hospital, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, Guangzhou, China
| | - Xiaoyan Xie
- Department of Medical Ultrasonics, The First Affiliated Hospital, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, Guangzhou, China
| | - Ming Xu
- Department of Medical Ultrasonics, The First Affiliated Hospital, Institute of Diagnostic and Interventional Ultrasound, Sun Yat-Sen University, Guangzhou, China
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Bodas de plata: 25 años de la primera demostración del efecto directo del fósforo en la célula paratiroidea. Nefrologia 2022. [DOI: 10.1016/j.nefro.2021.12.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Tsai WC, Wu HY, Chiu YL, Yang JY, Pai MF, Wu YR, Lin WY, Hung KY, Chien KL, Hsu SP, Peng YS. Acute effects of dietary phosphorus intake on markers of mineral metabolism in hemodialysis patients: post hoc analysis of a randomized crossover trial. Ren Fail 2021; 43:141-148. [PMID: 33427559 PMCID: PMC7808738 DOI: 10.1080/0886022x.2020.1870138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Background Long-term dietary phosphorus excess influences disturbances in mineral metabolism, but it is unclear how rapidly the mineral metabolism responds to short-term dietary change in dialysis populations. Methods This was a post hoc analysis of a randomized crossover trial that evaluated the short-term effects of low-phosphorus diets on mineral parameters in hemodialysis patients. Within a 9-day period, we obtained a total of 4 repeated measurements for each participant regarding dietary intake parameters, including calorie, phosphorus, and calcium intake, and markers of mineral metabolism, including phosphate, calcium, intact parathyroid hormone (iPTH), intact fibroblast growth factor 23 (iFGF23), and C-terminal fibroblast growth factor 23 (cFGF23). The correlations between dietary phosphorus intake and serum mineral parameters were assessed by using mixed-effects models. Results Thirty-four patients were analyzed. In the fully adjusted model, we found that an increase in dietary phosphorus intake of 100 mg was associated with an increase in serum phosphate of 0.3 mg/dL (95% confidence intervals [CI], 0.2–0.4, p < .001), a decrease in serum calcium of 0.06 mg/dL (95% CI, −0.11 to −0.01, p = .01), an increase in iPTH of 5.4% (95% CI, 1.4–9.3, p = .01), and an increase in iFGF23 of 5.0% (95% CI, 2.0–8.0, p = .001). Dietary phosphorus intake was not related to cFGF23. Conclusions Increased dietary phosphorus intake acutely increases serum phosphate, iPTH, and iFGF23 levels and decreases serum calcium levels, highlighting the important role of daily fluctuations of dietary habits in disturbed mineral homeostasis in hemodialysis patients.
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Affiliation(s)
- Wan-Chuan Tsai
- Division of Nephrology, Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan.,Center for General Education, Lee-Ming Institute of Technology, New Taipei City, Taiwan
| | - Hon-Yen Wu
- Division of Nephrology, Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan.,Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei City, Taiwan.,Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei City, Taiwan.,Faculty of Medicine, School of Medicine, National Yang-Ming University, Taipei City, Taiwan
| | - Yen-Ling Chiu
- Division of Nephrology, Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan.,Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei City, Taiwan.,Graduate Program in Biomedical Informatics, Yuan Ze University, Taoyuan City, Taiwan
| | - Ju-Yeh Yang
- Division of Nephrology, Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan.,Center for General Education, Lee-Ming Institute of Technology, New Taipei City, Taiwan.,Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei City, Taiwan
| | - Mei-Fen Pai
- Division of Nephrology, Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan.,Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei City, Taiwan
| | - Yong-Ru Wu
- Dietary Department, Far Eastern Memorial Hospital, New Taipei City, Taiwan
| | - Wan-Yu Lin
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei City, Taiwan
| | - Kuan-Yu Hung
- Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei City, Taiwan
| | - Kuo-Liong Chien
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei City, Taiwan.,Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei City, Taiwan
| | - Shih-Ping Hsu
- Division of Nephrology, Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan.,Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei City, Taiwan
| | - Yu-Sen Peng
- Division of Nephrology, Department of Internal Medicine, Far Eastern Memorial Hospital, New Taipei City, Taiwan.,Department of Internal Medicine, National Taiwan University Hospital and College of Medicine, Taipei City, Taiwan.,Department of Applied Cosmetology, Lee-Ming Institute of Technology, New Taipei City, Taiwan.,Department of Healthcare Administration, Oriental Institute of Technology, New Taipei City, Taiwan
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Sprague SM, Martin KJ, Coyne DW. Phosphate Balance and CKD-Mineral Bone Disease. Kidney Int Rep 2021; 6:2049-2058. [PMID: 34386654 PMCID: PMC8343779 DOI: 10.1016/j.ekir.2021.05.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 05/10/2021] [Indexed: 12/29/2022] Open
Abstract
Chronic kidney disease–mineral bone disorder (CKD-MBD) is a common comorbidity in patients with CKD. Characterized by laboratory abnormalities, bone abnormality, and vascular calcification, CKD-MBD encompasses a group of mineral and hormone disturbances that are strongly associated with increased cardiovascular (CV) morbidity and mortality. Abnormal serum phosphate concentrations are an independent risk factor for CV morbidity and mortality, and overall mortality. Phosphate retention plays a central role in initiating and driving many other disturbances in CKD-MBD (e.g., increased parathyroid hormone and fibroblast growth factor 23 concentrations, hypocalcemia, low vitamin D) that are also linked to increased CV risk. Thus, effective phosphate control is a logical therapeutic target for CKD-MBD treatment. Current phosphate management strategies (dietary restrictions, dialysis, phosphate binders) are insufficient to consistently achieve and maintain target phosphate concentrations in patients on dialysis. Phosphate binders reduce available phosphate for intestinal absorption but do not impair the dominant phosphate absorption pathway. Novel therapies that consider new mechanistic understandings of intestinal phosphate absorption are needed. One such therapy is tenapanor, a targeted sodium-hydrogen exchanger isoform 3 inhibitor that has been shown to reduce serum phosphate concentrations in multiple clinical trials. Tenapanor has a novel mechanism of action that reduces intestinal phosphate absorption in the primary paracellular phosphate absorption pathway.
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Affiliation(s)
- Stuart M Sprague
- Division of Nephrology and Hypertension, NorthShore University Health System, Evanston, IL, USA
| | | | - Daniel W Coyne
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
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Franchetti Y, Nolin TD. Application of Individualized PBPK Modeling of Rate Data to Evaluate the Effect of Hemodialysis on Nonrenal Clearance Pathways. J Clin Pharmacol 2021; 61:769-781. [PMID: 33459400 DOI: 10.1002/jcph.1818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 01/11/2021] [Indexed: 11/06/2022]
Abstract
The aim of this study was to apply individualized, physiologically based pharmacokinetic modeling of 14 CO2 production rates (iPBPK-R) measured by the erythromycin breath test to characterize the effect of hemodialysis on the function of nonrenal clearance pathways in patients with end-stage renal disease. Twelve patients previously received 14 C-erythromycin intravenously pre- and post-hemodialysis. Serial breath samples were collected after each dose over 2 hours. Eight PBPK parameters were co-estimated across periods, whereas activity of cytochrome P450 (CYP) 3A4 clearance was independently estimated for each period. Inhibition coefficients for organic anion transporting polypeptide (OATP), P-glycoprotein, and multidrug resistance-associated protein 2 activities were also estimated. Nonrenal clearance parameter estimates were explored regarding sex differences and correlations with uremic toxins and were used in hierarchical cluster analysis (HCA). Relationships between the function of nonrenal clearance pathways and uremic toxin concentrations were explored. Mean CYP 3A4 clearance increased by 2.2% post-hemodialysis. Uptake transporter activity was highly intervariable across hemodialysis. Females had 22% and 30% higher median CYP3A4 activity than males pre- and post-hemodialysis, respectively. Exploratory HCA indicated that using both CYP3A4 and OATP activity parameters at pre- and post-hemodialysis best identifies heterogeneous patients. This is the first study to use the iPBPK-R approach to simultaneously estimate multiple in vivo nonrenal elimination pathways in individual patients with kidney disease and to assess the effect of hemodialysis.
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Affiliation(s)
- Yoko Franchetti
- Department of Pharmaceutical Sciences, Center for Clinical Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania, USA
| | - Thomas D Nolin
- Department of Pharmacy and Therapeutics, Center for Clinical Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, Pennsylvania, USA
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Li D, Guo B, Liang Q, Liu Y, Zhang L, Hu N, Zhang X, Yang F, Ruan C. Tissue-engineered parathyroid gland and its regulatory secretion of parathyroid hormone. J Tissue Eng Regen Med 2020; 14:1363-1377. [PMID: 32511868 DOI: 10.1002/term.3080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 11/11/2022]
Abstract
Parathyroid glands (PTGs) are important endocrine organs being mainly responsible for the secretion of parathyroid hormone (PTH) to regulate the balance of calcium (Ca) /phosphorus (P) ions in the body. Once PTGs get injured or removed, their resulting defect or loss of PTH secretion should disturb the level of Ca/P in blood, thus damaging other related organs (bone, kidney, etc.) and even causing death. Recently, tissue-engineered PTGs (TE-PTGs) have attracted lots of attention as a potential treatment for the related diseases of PTGs caused by hypoparathyroidism and hyperparathyroidism, including tetany, muscle cramp, nephrolithiasis, nephrocalcinosis, and osteoporosis. Although great progress has been made in the establishment of TE-PTGs with an effective strategy to integrate the key factors of cells and biomaterials, its regulatory secretion of PTH to mimic its natural rhythms in the body remains a huge challenge. This review comprehensively describes an overview of PTGs from physiology and pathology to cytobiology and tissue engineering. The state of the arts in TE-PTGs and the feasible strategies to regulate PTH secretion behaviors are highlighted to provide an important foundation for further investigation.
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Affiliation(s)
- Duo Li
- Research Center for Human Tissue and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, PR China.,University of Chinese Academy of Sciences, Beijing, PR China
| | - Baochun Guo
- Department of Nephrology, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, PR China.,Key Laboratory of Shenzhen Renal Diseases, Shenzhen, PR China
| | - Qingfei Liang
- Research Center for Human Tissue and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, PR China.,University of Chinese Academy of Sciences, Beijing, PR China
| | - Yunhui Liu
- University of Chinese Academy of Sciences, Beijing, PR China.,The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, PR China
| | - Lu Zhang
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, PR China
| | - Nan Hu
- Department of Nephrology, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, PR China.,Key Laboratory of Shenzhen Renal Diseases, Shenzhen, PR China
| | - Xinzhou Zhang
- Department of Nephrology, Shenzhen People's Hospital (The Second Clinical Medical College, Jinan University; The First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, PR China.,Key Laboratory of Shenzhen Renal Diseases, Shenzhen, PR China
| | - Fan Yang
- University of Chinese Academy of Sciences, Beijing, PR China.,The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, PR China
| | - Changshun Ruan
- Research Center for Human Tissue and Organs Degeneration, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, PR China.,University of Chinese Academy of Sciences, Beijing, PR China
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Cinacalcet studies in pediatric subjects with secondary hyperparathyroidism receiving dialysis. Pediatr Nephrol 2020; 35:1679-1697. [PMID: 32367309 PMCID: PMC7385021 DOI: 10.1007/s00467-020-04516-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 02/18/2020] [Accepted: 02/21/2020] [Indexed: 12/16/2022]
Abstract
BACKGROUND Secondary hyperparathyroidism (sHPT), a complication of chronic kidney disease (CKD) characterized by persistently elevated parathyroid hormone (PTH), alterations in calcium-phosphorus homeostasis, and vitamin D metabolism, affects 50% of children receiving dialysis. A significant proportion of these children develop CKD-mineral and bone disorder (CKD-MBD), associated with an increased risk of fractures and vascular calcification. The standard of care for sHPT in children includes vitamin D sterols, calcium supplementation, and phosphate binders. Several agents are approved for sHPT treatment in adults undergoing dialysis, including vitamin D analogs and calcimimetics, with limited information on their safety and efficacy in children. The calcimimetic cinacalcet is approved for use in adults with sHPT on dialysis, but is not approved for pediatric use outside Europe. METHODS This review provides dosing, safety, and efficacy information from Amgen-sponsored cinacalcet pediatric trials and data from non-Amgen sponsored clinical studies. RESULTS The Amgen cinacalcet pediatric clinical development program consisted of two Phase 3 randomized studies, one Phase 3 single arm extension study, one open-label Phase 2 study, and two open-label Phase 1 studies. Effects of cinacalcet on PTH varied across studies. Overall, 7.4 to 57.1% of subjects who received cinacalcet in an Amgen clinical trial attained PTH levels within recommended target ranges and 22.2 to 70.6% observed a ≥ 30% reduction in PTH. In addition, significant reductions in PTH were demonstrated in all non-Amgen-supported studies. CONCLUSIONS To help inform the pediatric nephrology community, this manuscript contains the most comprehensive review of cinacalcet usage in pediatric CKD patients to date.
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Wang M, Obi Y, Streja E, Rhee CM, Chen J, Hao C, Kovesdy CP, Kalantar-Zadeh K. Impact of residual kidney function on hemodialysis adequacy and patient survival. Nephrol Dial Transplant 2019; 33:1823-1831. [PMID: 29688442 DOI: 10.1093/ndt/gfy060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 02/21/2018] [Indexed: 11/14/2022] Open
Abstract
Background Both dialysis dose and residual kidney function (RKF) contribute to solute clearance and are associated with outcomes in hemodialysis patients. We hypothesized that the association between dialysis dose and mortality is attenuated with greater RKF. Methods Among 32 251 incident hemodialysis patients in a large US dialysis organization (2007-11), we examined the interaction between single-pool Kt/V (spKt/V) and renal urea clearance (rCLurea) levels in survival analyses using multivariable Cox proportional hazards regression model. Results The median rCLurea and mean baseline spKt/V were 3.06 [interquartile range (IQR) 1.74-4.85] mL/min/1.73 m2 and 1.32 ± 0.28, respectively. A total of 7444 (23%) patients died during the median follow-up of 1.2 years (IQR 0.5-2.2 years) with an incidence of 15.4 deaths per 100 patient-years. The Cox model with adjustment for case-mix and laboratory variables showed that rCLurea modified the association between spKt/V and mortality (Pinteraction = 0.03); lower spKt/V was associated with higher mortality among patients with low rCLurea (i.e. <3 mL/min/1.73 m2) but not among those with higher rCLurea. The adjusted mortality hazard ratios (aHRs) and 95% confidence intervals of the low (<1.2) versus high (≥1.2) spKt/V were 1.40 (1.12-1.74), 1.21 (1.10-1.33), 1.06 (0.98-1.14), and 1.00 (0.93-1.08) for patients with rCLurea of 0.0, 1.0, 3.0 and 6.0 mL/min/1.73 m2, respectively. Conclusions Incident hemodialysis patients with substantial RKF do not exhibit the expected better survival at higher hemodialysis doses. RKF levels should be taken into account when deciding on the dose of dialysis treatment among incident hemodialysis patients.
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Affiliation(s)
- Mengjing Wang
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, Department of Medicine, University of California Irvine Medical Center, Orange, CA, USA.,Division of Nephrology, Department of Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Yoshitsugu Obi
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, Department of Medicine, University of California Irvine Medical Center, Orange, CA, USA
| | - Elani Streja
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, Department of Medicine, University of California Irvine Medical Center, Orange, CA, USA.,Nephrology Section, Tibor Rubin Veterans Affairs Medical Center, Long Beach, CA, USA
| | - Connie M Rhee
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, Department of Medicine, University of California Irvine Medical Center, Orange, CA, USA.,Nephrology Section, Tibor Rubin Veterans Affairs Medical Center, Long Beach, CA, USA
| | - Jing Chen
- Division of Nephrology, Department of Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Chuanming Hao
- Division of Nephrology, Department of Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Csaba P Kovesdy
- Division of Nephrology, Department of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA.,Nephrology Section, Memphis VA Medical Center, Memphis, TN, USA
| | - Kamyar Kalantar-Zadeh
- Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, Department of Medicine, University of California Irvine Medical Center, Orange, CA, USA.,Nephrology Section, Tibor Rubin Veterans Affairs Medical Center, Long Beach, CA, USA.,Fielding School of Public Health at UCLA, Los Angeles, CA, USA
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10
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FGF23, Biomarker or Target? Toxins (Basel) 2019; 11:toxins11030175. [PMID: 30909513 PMCID: PMC6468608 DOI: 10.3390/toxins11030175] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 03/14/2019] [Accepted: 03/19/2019] [Indexed: 12/11/2022] Open
Abstract
Fibroblast growth factor 23 (FGF23) plays a key role in the complex network between the bones and other organs. Initially, it was thought that FGF23 exclusively regulated phosphate and vitamin D metabolism; however, recent research has demonstrated that an excess of FGF23 has other effects that may be detrimental in some cases. The understanding of the signaling pathways through which FGF23 acts in different organs is crucial to develop strategies aiming to prevent the negative effects associated with high FGF23 levels. FGF23 has been described to have effects on the heart, promoting left ventricular hypertrophy (LVH); the liver, leading to production of inflammatory cytokines; the bones, inhibiting mineralization; and the bone marrow, by reducing the production of erythropoietin (EPO). The identification of FGF23 receptors will play a remarkable role in future research since its selective blockade might reduce the adverse effects of FGF23. Patients with chronic kidney disease (CKD) have very high levels of FGF23 and may be the population suffering from the most adverse FGF23-related effects. The general population, as well as kidney transplant recipients, may also be affected by high FGF23. Whether the association between FGF23 and clinical events is causal or casual remains controversial. The hypothesis that FGF23 could be considered a therapeutic target is gaining relevance and may become a promising field of investigation in the future.
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11
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Rodríguez-Ortiz ME, Pendón-Ruiz de Mier MV, Rodríguez M. Parathyroidectomy in dialysis patients: Indications, methods, and consequences. Semin Dial 2019; 32:444-451. [PMID: 30656752 DOI: 10.1111/sdi.12772] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Secondary hyperparathyroidism, characterized by increased PTH synthesis and secretion, is often seen in advanced stages of chronic kidney disease. Excessive proliferation of parathyroid cells leads to the development of diffuse hyperplasia that subsequently progresses to nodular histology. Refractory hyperparathyroidism occurs when parathyroid glands fail to respond to medical therapy. Parathyroidectomy (PTX), surgical resection of parathyroid glands, is usually performed in cases of persistent serum levels of PTH above 1000 pg/mL associated with hypercalcemia or when hyperparathyroidism is refractory to conservative therapy. Parathyroidectomy can be carried out using different procedures: subtotal PTX or total PTX with or without parathyroid autotransplantation. Parathyroid surgery may have undesirable consequences due to PTH oversuppression, such as the development of adynamic bone disease; hungry bone syndrome is quite common after this surgery. However, PTX improves survival and parameters of mineral metabolism. Parathyroidectomy needs to be considered in those patients with severe hyperparathyroidism with a poor response to pharmacological treatment and with distinct undesirable effects of PTH on bone and mineral metabolism parameters.
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Affiliation(s)
- María E Rodríguez-Ortiz
- Maimónides Institute for Biomedical Research (IMIBIC), Córdoba, Spain.,Reina Sofía University Hospital, Córdoba, Spain.,University of Córdoba, Córdoba, Spain.,Spanish Renal Research Network (REDinREN), Institute of Health Carlos III, Madrid, Spain
| | - María V Pendón-Ruiz de Mier
- Maimónides Institute for Biomedical Research (IMIBIC), Córdoba, Spain.,Reina Sofía University Hospital, Córdoba, Spain.,University of Córdoba, Córdoba, Spain.,Spanish Renal Research Network (REDinREN), Institute of Health Carlos III, Madrid, Spain
| | - Mariano Rodríguez
- Maimónides Institute for Biomedical Research (IMIBIC), Córdoba, Spain.,University of Córdoba, Córdoba, Spain.,Spanish Renal Research Network (REDinREN), Institute of Health Carlos III, Madrid, Spain.,Nephrology Service, University Hospital Reina Sofía, Córdoba, Spain
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12
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Portillo MR, Rodríguez-Ortiz ME. Secondary Hyperparthyroidism: Pathogenesis, Diagnosis, Preventive and Therapeutic Strategies. Rev Endocr Metab Disord 2017; 18:79-95. [PMID: 28378123 DOI: 10.1007/s11154-017-9421-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Uremic secondary hyperparathyroidism is a multifactorial and complex disease often present in advanced stages of chronic kidney disease. The accumulation of phosphate, the increased FGF23 levels, the reduction in active vitamin D production, and the tendency to hypocalcemia are persistent stimuli for the development and progression of parathyroid hyperplasia with increased secretion of PTH. Parathyroid proliferation may become nodular mainly in cases of advanced hyperparathyroidism. The alterations in the regulation of mineral metabolism, the development of bone disease and extraosseous calcifications are essential components of chronic kidney disease-mineral and bone disorder and have been associated with negative outcomes. The management of hyperparathyroidism includes the correction of vitamin D deficiency and control of serum phosphorus and PTH without inducing hypercalcemia. An update of the leading therapeutic tools available for the prevention and clinical management of secondary hyperparathyroidism, its diagnosis, and the main mechanisms and factors involved in the pathogenesis of the disease will be described in this review.
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Affiliation(s)
- Mariano Rodríguez Portillo
- Nephrology Service, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Reina Sofía University Hospital/University of Córdoba, Avda. Menéndez Pidal, S/N, 14004, Córdoba, Spain.
- REDinREN, Madrid, Spain.
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13
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The impact of oat (Avena sativa) consumption on biomarkers of renal function in patients with chronic kidney disease: A parallel randomized clinical trial. Clin Nutr 2016; 37:78-84. [PMID: 28003041 DOI: 10.1016/j.clnu.2016.11.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Revised: 11/15/2016] [Accepted: 11/28/2016] [Indexed: 01/07/2023]
Abstract
BACKGROUND & OBJECTIVE Animal studies report that oat (Avena sativa L) intake has favorable effects on kidney function. However, the effects of oat consumption have not been assessed in humans. The aim of this study was to examine the impact of oat intake on biomarkers of renal function in patients with chronic kidney disease (CKD). METHODS Fifty-two patients with CKD were randomly assigned to a control group (recommended to reduce intake of dietary protein, phosphorus, sodium and potassium) or an oat consumption group (given nutritional recommendations for controls +50 g/day oats). Blood urea nitrogen (BUN), serum creatinine (SCr), urine creatinine, serum albumin, serum potassium, parathyroid hormone (PTH), serum klotho and urine protein concentration were measured at baseline and after an eight-week intervention. Creatinine clearance was calculated using urine creatinine concentration. RESULTS Within group analysis showed a significant increase in BUN (P = 0.02) and serum potassium (P = 0.01) and a marginally significant increment in SCr (P = 0.08) among controls. However, changes in the oat group were not significant. In a multivariate adjusted model, we observed a significant difference in change of serum potassium (-0.03 mEq/L for oat group and 0.13 mEq/L for control group; P = 0.01) and a marginally significant difference in change of serum albumin (0.01 g/dl for oat group and -0.08 for control group; P = 0.08) between the two groups. There was no change in PTH concentration. CONCLUSION Intake of oats may have a beneficial effect on serum albumin and serum potassium in patients with CKD. REGISTRATION CODE Present study registered under IRCT.ir identifier no. IRCT2015050414551N2.
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14
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Sesión de hemodiálisis: la tormenta perfecta para la calcificación vascular. Nefrologia 2015; 35:448-56. [DOI: 10.1016/j.nefro.2015.06.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 03/17/2015] [Indexed: 02/02/2023] Open
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15
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Valle C, Rodriguez M, Santamaría R, Almaden Y, Rodriguez ME, Cañadillas S, Martin-Malo A, Aljama P. Cinacalcet reduces the set point of the PTH-calcium curve. J Am Soc Nephrol 2008; 19:2430-6. [PMID: 18632847 DOI: 10.1681/asn.2007121320] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The calcimimetic cinacalcet increases the sensitivity of the parathyroid calcium-sensing receptor to calcium and therefore should produce a decrease in the set point of the parathyroid hormone (PTH)-calcium curve. For investigation of this hypothesis, nine long-term hemodialysis patients with secondary hyperparathyroidism were given cinacalcet for 2 mo, the dosage was titrated per a protocol based on intact PTH and plasma calcium concentrations. Dialysis against low- and high-calcium (0.75 and 1.75 mM) dialysate was used to generate curves describing the relationship between PTH and calcium. Compared with precinacalcet levels, cinacalcet significantly reduced mean serum calcium, intact PTH and whole PTH (wPTH; all P < 0.001). The set points for PTH-calcium curves were significantly reduced, and both maximum and minimum levels of PTH (intact and whole) were significantly decreased. The calcium-mediated inhibition of PTH secretion was more marked after cinacalcet treatment. In addition, cinacalcet shifted the inverse sigmoidal curve of wPTH/non-wPTH ratio versus calcium to the left (i.e., less calcium was required to reduce the wPTH/non-wPTH ratio). In conclusion, cinacalcet increases the sensitivity of the parathyroids to calcium, causing a marked reduction in the set point of the PTH-calcium curve, in hemodialysis patients with secondary hyperparathyroidism.
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Affiliation(s)
- Casimiro Valle
- Nephrology Service and Research Unit, Hospital Universitario Reina Sofía, Cordoba, Spain
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16
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de Francisco ALM, Izquierdo M, Cunningham J, Piñera C, Palomar R, Fresnedo GF, Amado JA, Unzueta MG, Arias M. Calcium-mediated parathyroid hormone release changes in patients treated with the calcimimetic agent cinacalcet. Nephrol Dial Transplant 2008; 23:2895-901. [PMID: 18424820 DOI: 10.1093/ndt/gfn191] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The parathyroid-calcium (Ca(2+)-PTH) curve expresses modulation of parathyroid hormone (PTH) secretion by the parathyroid gland as a function of changing extracellular Ca(2+) concentration. Patients with hyperparathyroidism (HPT) show a rightward shift of the curve compared with controls, suggesting a reduced sensitivity of parathyroid cells to Ca(2+). Increasing the sensitivity of the parathyroid gland to extracellular Ca(2+) by manipulation of the Ca(2+)-sensing receptor (CaR) may have therapeutic potential. Calcimimetics allosterically modify CaR and render it more sensitive to extracellular Ca(2+), accounting for the simultaneous reduction of Ca(2+) and PTH seen in most patients. METHODS The Ca(2+)-PTH curve was evaluated in 10 haemodialysis patients, with baseline intact PTH levels >300 pg/ml in two haemodialysis sessions, one before and the other after (range, 9-22 weeks) cinacalcet treatment. In each session a 2-h low-dialysate Ca(2+) concentration was used to induce hypocalcaemia and maximally stimulate PTH secretion, followed immediately by a 2-h high-dialysate Ca(2+) concentration to induce hypercalcaemia and maximally inhibit PTH secretion. RESULTS Significant decreases in ionized Ca(2+) and intact PTH were observed following cinacalcet treatment. Cinacalcet treatment also led to a decrease in the set point for Ca(2+) and to a leftward shift of the Ca(2+)-PTH curve. Significant differences were present in all segments of the Ca(2+)-PTH curves. CONCLUSION The pathological rightward shift of the Ca(2+)-PTH curve seen in many HPT patients may be reversed by cinacalcet treatment.
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Affiliation(s)
- Angel L M de Francisco
- Servicio de Nefrología, Hospital Universitario Valdecilla, Avda Valdecilla, s/n, Santander, 39008, Spain.
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17
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Felsenfeld AJ, Rodríguez M, Aguilera-Tejero E. Dynamics of parathyroid hormone secretion in health and secondary hyperparathyroidism. Clin J Am Soc Nephrol 2007; 2:1283-305. [PMID: 17942777 DOI: 10.2215/cjn.01520407] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This review examines the dynamics of parathyroid hormone secretion in health and in various causes of secondary hyperparathyroidism. Although most studies of parathyroid hormone and calcium have focused on the modification of parathyroid hormone secretion by serum calcium, the relationship between parathyroid hormone and serum calcium is bifunctional because parathyroid hormone also modifies serum calcium. In normal animals and humans, factors such as phosphorus and vitamin D modify the basal parathyroid hormone level and the maximal parathyroid hormone response to hypocalcemia. Certain medications, such as lithium and estrogen, in normal individuals and sustained changes in the serum calcium concentration in hemodialysis patients change the set point of calcium, which reflects the serum calcium concentration at which parathyroid hormone secretion responds. Hypocalcemia increases the basal/maximal parathyroid hormone ratio, a measure of the relative degree of parathyroid hormone stimulation. The phenomenon of hysteresis, defined as a different parathyroid hormone value for the same serum calcium concentration during the induction of and recovery from hypo- and hypercalcemia, is discussed because it provides important insights into factors that affect parathyroid hormone secretion. In three causes of secondary hyperparathyroidism--chronic kidney disease, vitamin D deficiency, and aging--factors that affect the dynamics of parathyroid hormone secretion are evaluated in detail. During recovery from vitamin D deficiency, the maximal parathyroid hormone remains elevated while the basal parathyroid hormone value rapidly becomes normal because of a shift in the set point of calcium. Much remains to be learned about the dynamics of parathyroid hormone secretion in health and secondary hyperparathyroidism.
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Affiliation(s)
- Arnold J Felsenfeld
- Department of Medicine, VA Greater Los Angeles Healthcare System, 11301 Wilshire Boulevard, Los Angeles, CA 90073, USA.
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18
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Abstract
Renal osteodystrophy (ROD) develops as the early stages of chronic renal failure (CRF) and covers a spectrum of bone changes observed in the uraemic patient, which extend from high remodelling bone disease (frequently known as osteitis fibrosa) to low turnover, or adynamic disease. Between these two extremes there are also cases of bone mineralization compromised in variable degrees, as is the case of 'mixed bone disease' and osteomalacia. The dynamic process of bone remodelling is compromised in CRF, and a positive or negative bone balance can be observed in uraemic patients. In addition to the classic modulators of bone remodelling, like parathyroid hormone, calcitriol and calcitonin, other factors were recently identified as significant modulators of osteoblast and osteoclast activation in uraemic patients. In fact, different cytokines and growth factors, acting at an autocrine or paracrine level, seem to play a relevant role in the bone and mineral changes observed in uraemia. Recently, observations have been made of the development of more sensitive and specific techniques to assay different biochemical markers of bone turnover and mineral metabolism. Analogously, new contributions of conventional bone histology, bone immunocytochemistry and molecular biology, which enabled the understanding of some etiopathogenic mechanisms of ROD, were observed.
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Affiliation(s)
- A Ferreira
- Hospital Curry Cabral, Universidade Nova de Lisboa, Lisbon, Portugal.
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19
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Yavuz A, Tetta C, Ersoy FF, D'intini V, Ratanarat R, De Cal M, Bonello M, Bordoni V, Salvatori G, Andrikos E, Yakupoglu G, Levin NW, Ronco C. Uremic toxins: a new focus on an old subject. Semin Dial 2005; 18:203-11. [PMID: 15934967 DOI: 10.1111/j.1525-139x.2005.18313.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The uremic syndrome is characterized by an accumulation of uremic toxins due to inadequate kidney function. The European Uremic Toxin (EUTox) Work Group has listed 90 compounds considered to be uremic toxins. Sixty-eight have a molecular weight less than 500 Da, 12 exceed 12,000 Da, and 10 have a molecular weight between 500 and 12,000 Da. Twenty-five solutes (28%) are protein bound. The kinetics of urea removal is not representative of other molecules such as protein-bound solutes or the middle molecules, making Kt/V misleading. Clearances of urea, even in well-dialyzed patients, amount to only one-sixth of physiological clearance. In contrast to native kidney function, the removal of uremic toxins in dialysis is achieved by a one-step membrane-based process and is intermittent. The resulting sawtooth plasma concentrations of uremic toxins contrast with the continuous function of native kidneys, which provides constant solute clearances and mass removal rates. Our increasing knowledge of uremic toxins will help guide future treatment strategies to remove them.
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Affiliation(s)
- Asuman Yavuz
- Division of Nephrology and Transplantation, Akdeniz University, Antalya, Turkey
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20
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Rodriguez M, Nemeth E, Martin D. The calcium-sensing receptor: a key factor in the pathogenesis of secondary hyperparathyroidism. Am J Physiol Renal Physiol 2004; 288:F253-64. [PMID: 15507543 DOI: 10.1152/ajprenal.00302.2004] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Serum calcium levels are regulated by the action of parathyroid hormone (PTH). Major drivers of PTH hypersecretion and parathyroid cell proliferation are the hypocalcemia and hyperphosphatemia that develop in chronic kidney disease patients with secondary hyperparathyroidism (SHPT) as a result of low calcitriol levels and decreased kidney function. Increased PTH production in response to systemic hypocalcemia is mediated by the calcium-sensing receptor (CaR). Furthermore, as SHPT progresses, reduced expression of CaRs and vitamin D receptors (VDRs) in hyperplastic parathyroid glands may limit the ability of calcium and calcitriol to regulate PTH secretion. Current treatment for SHPT includes the administration of vitamin D sterols and phosphate binders. Treatment with vitamin D is initially effective, but efficacy often wanes with further disease progression. The actions of vitamin D sterols are undermined by reduced expression of VDRs in the parathyroid gland. Furthermore, the calcemic and phosphatemic actions of vitamin D mean that it has the potential to exacerbate abnormal mineral metabolism, resulting in the formation of vascular calcifications. Effective new treatments for SHPT that have a positive impact on mineral metabolism are clearly needed. Recent research shows that drugs that selectively target the CaR, calcimimetics, have the potential to meet these requirements.
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Affiliation(s)
- Mariano Rodriguez
- Unidad de Investigación, Servicio de Nefrologia, Hospital Universitario Reina Sofía, Avd Menendez Pidal s/n, 14004 Cordoba, Spain.
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21
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Abstract
The uremic syndrome is the result of the retention of solutes, which under normal conditions are cleared by the healthy kidneys. Uremic retention products are arbitrarily subdivided according to their molecular weight. Low-molecular-weight molecules are characterized by a molecular weight below 500 D. The purpose of the present publication is to review the main water soluble, nonprotein bound uremic retention solutes, together with their main toxic effects. We will consecutively discuss creatinine, glomerulopressin, the guanidines, the methylamines, myo-inositol, oxalate, phenylacetyl-glutamine, phosphate, the polyamines, pseudouridine, the purines, the trihalomethanes, and urea per se.
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Jara A, Chacón C, Felsenfeld AJ. Hyperphosphatemia modestly retards parathyroid hormone suppression during calcitriol-induced hypercalcemia in normal and azotemic rats. Nephron Clin Pract 2002; 92:883-8. [PMID: 12399635 DOI: 10.1159/000065454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS In in vitro studies, a high phosphate concentration has been shown to directly stimulate parathyroid hormone (PTH) secretion in a normal calcium concentration and to reduce PTH suppression in a high calcium concentration. In hemodialysis patients during dialysis-induced hypercalcemia, the effect of hyperphosphatemia on PTH secretion was less than in vitro studies. Our goal was to determine whether hyperphosphatemia retards PTH suppression during calcitriol-induced hypercalcemia in azotemic rats with hyperparathyroidism. METHODS Rats underwent a two-stage 5/6 nephrectomy or sham operations. After surgery, rats received a high phosphate diet (P 1.2%, Ca 0.6%) for 4 weeks to induce hyperparathyroidism and then were placed on a normal diet (P 0.6%, Ca 0.6%) for two additional weeks to normalize serum calcium values in azotemic rats. At week 7, rats were divided into five groups and before sacrifice received at 24-hour intervals, three doses of calcitriol (CTR) or its vehicle. The five groups and dietary phosphate content were: group 1--normal renal function (NRF) + 0.6% P + vehicle; group 2--NRF + 0.6% P + CTR; group 3--renal failure (RF) + 0.6% P + vehicle; group 4--RF + 1.2% P + CTR; and group 5--RF + 0.6% P + CTR. RESULTS In the two CTR-treated groups with marked hypercalcemia (groups 2 and 5), 15.52 +/- 0.26 and 15.12 +/- 0.13 mg/dl, respectively, stepwise regression showed that hyperphosphatemia retarded PTH suppression. When the two azotemic groups treated with CTR (groups 4 and 5) were combined to expand the range of serum calcium values, stepwise regression showed that hypercalcemia suppressed and hyperphosphatemia modestly retarded PTH suppression. Similarly, in groups 4 and 5 combined, correlations were present between PTH and both serum calcium (r = -0.70, p < 0.001) and serum phosphate (r = 0.64, p = 0.001). CONCLUSIONS Hypercalcemia and high doses of calcitriol markedly reduced PTH secretion in azotemic rats despite severe hyperphosphatemia. Even though hyperphosphatemia did retard PTH suppression during hypercalcemia, its effect was small.
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Affiliation(s)
- Aquiles Jara
- Department of Nephrology, Pontificia Universidad Católica de Chile, Santiago, Chile.
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Rodriguez M, Canalejo A, Garfia B, Aguilera E, Almaden Y. Pathogenesis of refractory secondary hyperparathyroidism. KIDNEY INTERNATIONAL. SUPPLEMENT 2002:155-60. [PMID: 11982830 DOI: 10.1046/j.1523-1755.61.s80.26.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Calcitriol is currently used to reduce parathyroid hormone (PTH) levels in uremic patients. However, a significant number of patients fail to respond to calcitriol therapy. The data suggest that a poor response to calcitriol can be anticipated in patients with severe hyperparathyroidism (with a high basal PTH levels) and uncontrolled serum phosphate. The abnormal parathyroid response to calcitriol in uremic patients with severe parathyroid hyperplasia may be attributed, to a large extent, to the development of nodular hyperplasia as a result of clonal transformation from a diffuse polyclonal hyperplasia. The factors involved in the development of polyclonal parathyroid hyperplasia, at earlier stages of secondary hyperparathyroidism, appear to be the same factors that stimulate PTH secretion and synthesis: hypocalcemia, hyperphosphatemia and low serum calcitriol levels. Studies performed in vitro using parathyroid tissue from uremic patients who required parathyroidectomy demonstrate that in nodular hyperplasia there is an abnormal response to calcium and calcitriol, which suggests that there are factors intrinsic to the hyperplastic cell (such as decrease in calcium sensor receptors and vitamin D receptors) responsible for an abnormal regulation of parathyroid function. Accumulation of phosphate is a key factor in the pathogenesis of secondary hyperparathyroidism and a poor response to calcitriol treatment is associated with the failure to control the serum phosphorus. High phosphate stimulates PTH secretion as demonstrated by in vivo and in vitro studies. In addition, animal studies strongly suggest that phosphate increases parathyroid cell proliferation. There are growth-related genes potentially involved in uremic hyperparathyroidism; however, changes in the expression of these genes may be the consequence rather than the cause of parathyroid hyperplasia.
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Affiliation(s)
- Mariano Rodriguez
- Nephrology Services and Research Unit, Hospital Universitario Reina Sofia, Córdoba, Spain.
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Almadén Y, Canalejo A, Ballesteros E, Añón G, Cañadillas S, Rodríguez M. Regulation of arachidonic acid production by intracellular calcium in parathyroid cells: effect of extracellular phosphate. J Am Soc Nephrol 2002; 13:693-698. [PMID: 11856773 DOI: 10.1681/asn.v133693] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The action of extracellular calcium on the calcium receptor in parathyroid cells results in activation of phospholipase C (PLC), PLD, and PLA(2). The PLA(2)-arachidonic acid (AA) intracellular signaling pathway mediates inhibition of parathyroid hormone (PTH) secretion. In addition, stimulation of the calcium receptor produces increases in intracellular calcium levels. It was demonstrated that high extracellular phosphate levels reduce the production of AA, a mechanism by which phosphate may stimulate PTH secretion. The objective was to determine, in parathyroid tissue, whether AA production is stimulated by increases in intracellular calcium levels and to investigate whether the decreased AA production induced by high extracellular phosphate levels could be modified by increases in intracellular calcium levels. Experiments were performed in vitro using parathyroid tissue. The intracellular calcium level was increased by incubation with an ionophore (A23187), which increases calcium influx across the cell membrane, or thapsigargin, which releases calcium from intracellular stores. The phosphate concentration in the medium was normal (1 mM) or high (4 mM). The response to calcium was evaluated by incubation with 0.6 or 1.35 mM calcium concentrations. AA production by parathyroid tissue was measured by gas chromatography. In parathyroid tissue incubated with either a calcium ionophore or thapsigargin, there was an increase in AA production, together with inhibition of PTH secretion, suggesting that PLA(2) is activated by the elevation in intracellular calcium levels. Therefore, the effect of intracellular calcium level elevation on AA production in the presence of high extracellular phosphate levels was evaluated. The results demonstrate that, despite high phosphate levels in the medium, both the ionophore and thapsigargin were capable of inducing a marked increase in AA production, which was associated with a decrease in PTH secretion. In conclusion, in parathyroid tissue, AA levels can be regulated by an ionophore and thapsigargin, both of which increase cytosolic calcium concentrations. The stimulation of PTH secretion by high phosphate levels can be prevented by increases in intracellular calcium levels.
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Affiliation(s)
- Yolanda Almadén
- *Research Unit and Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain; Department of Environmental Biology and Public Health, University of Huelva, Huelva, Spain; and Department of Physical and Analytical Chemistry, Technical University School of Linares, University of Jaen, Jaen, Spain
| | - Antonio Canalejo
- *Research Unit and Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain; Department of Environmental Biology and Public Health, University of Huelva, Huelva, Spain; and Department of Physical and Analytical Chemistry, Technical University School of Linares, University of Jaen, Jaen, Spain
| | - Evaristo Ballesteros
- *Research Unit and Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain; Department of Environmental Biology and Public Health, University of Huelva, Huelva, Spain; and Department of Physical and Analytical Chemistry, Technical University School of Linares, University of Jaen, Jaen, Spain
| | - Gracia Añón
- *Research Unit and Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain; Department of Environmental Biology and Public Health, University of Huelva, Huelva, Spain; and Department of Physical and Analytical Chemistry, Technical University School of Linares, University of Jaen, Jaen, Spain
| | - Sagrario Cañadillas
- *Research Unit and Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain; Department of Environmental Biology and Public Health, University of Huelva, Huelva, Spain; and Department of Physical and Analytical Chemistry, Technical University School of Linares, University of Jaen, Jaen, Spain
| | - Mariano Rodríguez
- *Research Unit and Nephrology Service, Reina Sofia University Hospital, Cordoba, Spain; Department of Environmental Biology and Public Health, University of Huelva, Huelva, Spain; and Department of Physical and Analytical Chemistry, Technical University School of Linares, University of Jaen, Jaen, Spain
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25
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Andress DL. New Therapies Raise New Issues for Lowering Parathyroid Hormone Levels in Uremic Patients. Semin Dial 2002. [DOI: 10.1046/j.1525-139x.1999.99041.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Dennis L. Andress
- Departments of Medicine and Research, VA Medical Center, University of Washington School of Medicine, Seattle, Washington
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Abstract
During the past review year, researchers have discovered the molecular pathogeneses of disorders of calcium, vitamin D and bone. This review discusses the roles of the extracellular calcium sensor, the renal 25-hydroxyvitamin D-1-alpha-hydroxylase, the vitamin D receptor, and new factors for bone cell embryogenesis and function as a way of introduction to this exciting area of medicine.
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Affiliation(s)
- C B Langman
- Department of Pediatrics, Northwestern University, Evanston, Illinois, USA.
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27
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Wada M, Nagano N, Furuya Y, Chin J, Nemeth EF, Fox J. Calcimimetic NPS R-568 prevents parathyroid hyperplasia in rats with severe secondary hyperparathyroidism. Kidney Int 2000; 57:50-8. [PMID: 10620187 DOI: 10.1046/j.1523-1755.2000.00837.x] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
UNLABELLED Calcimimetic NPS R-568 prevents parathyroid hyperplasia in rats with severe secondary hyperparathyroidism. BACKGROUND Secondary hyperparathyroidism (secondary HPT) in chronic renal insufficiency (CRI) is characterized by multiglandular hyperplasia. METHODS In this study, we investigated the effects of the calcimimetic NPS R-568 on the parathyroid gland in rats with CRI induced by ligation of the renal arteries and severe secondary HPT induced by dietary phosphorus loading. Six days after surgery, high-phosphorus diet feeding was started, and NPS R-568 was administered to the rats for 56 days either by daily gavage (30 or 100 micromol/kg) or by continuous subcutaneous infusion (20 micromol/kg. day). RESULTS After 54 days, serum PTH levels in vehicle-treated CRI rats were 1019 vs. 104 pg/mL in sham-operated controls. Infusion of NPS R-568 maintained serum PTH at levels comparable with those of sham-operated controls, whereas daily gavage also prevented much of the increase in CRI controls and decreased PTH levels intermittently in a dose-dependent fashion. Parathyroid gland enlargement was caused predominantly by hyperplasia. Total cell number per kg body wt was 3.5-fold higher in vehicle-treated CRI rats than in sham-operated controls. Both infusion and high-dose gavage of NPS R-568 completely prevented the increase in parathyroid cell number. CONCLUSION These results demonstrate that the calcimimetic compound NPS R-568 can prevent both the increase in serum PTH levels and parathyroid hyperplasia in rats with CRI and severe secondary HPT. Moreover, these changes occurred despite decreases in serum 1, 25(OH)2D3 and increases in serum phosphate, suggesting a dominant role for the calcium receptor in regulating parathyroid cell proliferation.
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Affiliation(s)
- M Wada
- Pharmaceutical Development Laboratory, Kirin Brewery Co; Ltd, Gunma, Japan
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28
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Estepa JC, Aguilera-Tejero E, Lopez I, Almaden Y, Rodriguez M, Felsenfeld AJ. Effect of phosphate on parathyroid hormone secretion in vivo. J Bone Miner Res 1999; 14:1848-54. [PMID: 10571684 DOI: 10.1359/jbmr.1999.14.11.1848] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Alterations in phosphate homeostasis play an important role in the development of secondary hyperparathyroidism in renal failure. Until recently, it was accepted that phosphate retention only increased parathyroid hormone (PTH) secretion through indirect mechanisms affecting calcium regulation and calcitriol synthesis. However, recent in vitro studies have suggested that phosphate may directly affect PTH secretion. Our goal was to determine whether in vivo an intravenous phosphate infusion stimulated PTH secretion in the absence of changes in serum calcium. Three different doses of phosphate were infused intravenously during 120 minutes to increase the serum phosphate concentration in dogs. Sulfate was also infused intravenously as a separate experimental control. A simultaneous calcium clamp was performed to maintain a normal ionized calcium concentration throughout all studies. At the lowest dose of infused phosphate (1.2 mmol/kg), serum phosphate values increased to approximately 3 mM, but PTH values did not increase. At higher doses of infused phosphate (1.6 mmol/kg and 2.4 mmol/kg), the increase in serum phosphate to values of approximately 4 mM and 5 mM, respectively, was associated with increases in PTH, even though the ionized calcium concentration did not change. Increases in PTH were not observed until 30-60 minutes into the study. These increases were not sustained, since by 120 minutes PTH values were not different from baseline or controls despite the maintenance of marked hyperphosphatemia. During the sulfate infusion, serum sulfate values increased by approximately 3-fold, but no change in PTH values were observed. In conclusion, an acute elevation in serum phosphate stimulated PTH secretion in the intact animal, but the magnitude of hyperphosphatemia exceeded the physiologic range. Future studies are needed to determine whether PTH stimulation is more sensitive to phosphate loading in states of chronic phosphate retention. Moreover, the mechanisms responsible for the delay in PTH stimulation and the failure to sustain the increased PTH secretion need further evaluation.
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Affiliation(s)
- J C Estepa
- Departamento de Medicina y Cirugía Animal Facultad de Veterinaria, Universidad de Cordoba, Cordoba, Spain
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29
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Rodriguez M, Caravaca F, Fernandez E, Borrego MJ, Lorenzo V, Cubero J, Martin-Malo A, Betriu A, Jimenez A, Torres A, Felsenfeld AJ. Parathyroid function as a determinant of the response to calcitriol treatment in the hemodialysis patient. Kidney Int 1999; 56:306-17. [PMID: 10411707 DOI: 10.1046/j.1523-1755.1999.00538.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Bolus calcitriol (CTR) is used for the treatment of secondary hyperparathyroidism in dialysis patients. Although CTR treatment reduces parathyroid hormone (PTH) levels in many dialysis patients, a significant number fail to respond. METHODS To learn whether or not an analysis of parathyroid function could further illuminate the response to CTR, a PTH-calcium curve was performed before and after at least two months of CTR treatment in 50 hemodialysis patients with a predialysis intact PTH of greater than 300 pg/ml. RESULTS For the entire group (N = 50), CTR treatment resulted in a 24% reduction in predialysis (basal) PTH from 773 +/- 54 to 583 +/- 71 pg/ml (P < 0.001), whereas ionized calcium increased from 1.10 +/- 0.02 to 1.22 +/- 0.02 mM (P < 0.001); however, maximal and minimal PTH did not change from pre-CTR values. Based on whether or not the basal PTH decreased by 40% or more during CTR treatment, patients were divided into responders (Rs, N = 25) and nonresponders (NRs, N = 25). Before CTR, the NR group was characterized by a greater basal (959 +/- 80 vs. 586 +/- 51 pg/ml, P < 0.001) and maximal (1899 +/- 170 vs. 1172 +/- 108 pg/ml, P < 0. 001) PTH and serum phosphorus (6.14 +/- 0.25 vs. 5.14 +/- 0.34 mg/dl, P < 0.01). Logistical regression analysis showed that the pre-CTR basal PTH was the most important predictor of the post-CTR basal PTH, and a pre-CTR basal PTH of 750 pg/ml represented a 50% probability of a response. Basal PTH correlated with the ionized calcium in the NR group (r = 0.59, P = 0.002) but not in the R group (r = 0.06, P = NS). In the R group, an inverse correlation was present between ionized calcium and the basal/maximal PTH ratio, an indicator of whether calcium is suppressing basal PTH secretion relative to the maximal secretory capacity (maximal PTH) r = -0.55, P = 0.004; in the NR group, this correlation approached significance but was positive (r = 0.34, P = 0.09). After CTR treatment, serum calcium increased in both groups, and despite marked differences in basal PTH (Rs, 197 +/- 25 vs. NRs, 969 +/- 85 pg/ml), an inverse correlation between ionized calcium and basal/maximal PTH was present in both groups (Rs, r = -0.61, P = 0.001, and NRs, r = -0.60, P = 0.001). CONCLUSIONS (a) Dynamic testing of parathyroid function provided insights into the pathophysiology of PTH secretion in hemodialysis patients. (b) The magnitude of hyperparathyroidism was the most important predictor of the response to CTR. (c) Before CTR treatment, PTH was sensitive to calcium in Rs, and serum calcium was PTH driven in NRs, and (d) after the CTR-induced increase in serum calcium, calcium suppressed basal PTH relative to maximal PTH in both groups.
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Affiliation(s)
- M Rodriguez
- Nephrology Services from the Hospital Universitario Reina Sofia, Cordoba, Spain.
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30
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Felsenfeld AJ, Rodriguez M. Phosphorus, regulation of plasma calcium, and secondary hyperparathyroidism: a hypothesis to integrate a historical and modern perspective. J Am Soc Nephrol 1999; 10:878-90. [PMID: 10203374 DOI: 10.1681/asn.v104878] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- A J Felsenfeld
- Department of Medicine, West Los Angeles VA Medical Center and UCLA, California 90073, USA.
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