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Abstract
IMPORTANCE Hypercalcemia affects approximately 1% of the worldwide population. Mild hypercalcemia, defined as total calcium of less than 12 mg/dL (<3 mmol/L) or ionized calcium of 5.6 to 8.0 mg/dL (1.4-2 mmol/L), is usually asymptomatic but may be associated with constitutional symptoms such as fatigue and constipation in approximately 20% of people. Hypercalcemia that is severe, defined as total calcium of 14 mg/dL or greater (>3.5 mmol/L) or ionized calcium of 10 mg/dL or greater (≥2.5 mmol/L) or that develops rapidly over days to weeks, can cause nausea, vomiting, dehydration, confusion, somnolence, and coma. OBSERVATIONS Approximately 90% of people with hypercalcemia have primary hyperparathyroidism (PHPT) or malignancy. Additional causes of hypercalcemia include granulomatous disease such as sarcoidosis, endocrinopathies such as thyroid disease, immobilization, genetic disorders, and medications such as thiazide diuretics and supplements such as calcium, vitamin D, or vitamin A. Hypercalcemia has been associated with sodium-glucose cotransporter 2 protein inhibitors, immune checkpoint inhibitors, denosumab discontinuation, SARS-CoV-2, ketogenic diets, and extreme exercise, but these account for less than 1% of causes. Serum intact parathyroid hormone (PTH), the most important initial test to evaluate hypercalcemia, distinguishes PTH-dependent from PTH-independent causes. In a patient with hypercalcemia, an elevated or normal PTH concentration is consistent with PHPT, while a suppressed PTH level (<20 pg/mL depending on assay) indicates another cause. Mild hypercalcemia usually does not need acute intervention. If due to PHPT, parathyroidectomy may be considered depending on age, serum calcium level, and kidney or skeletal involvement. In patients older than 50 years with serum calcium levels less than 1 mg above the upper normal limit and no evidence of skeletal or kidney disease, observation may be appropriate. Initial therapy of symptomatic or severe hypercalcemia consists of hydration and intravenous bisphosphonates, such as zoledronic acid or pamidronate. In patients with kidney failure, denosumab and dialysis may be indicated. Glucocorticoids may be used as primary treatment when hypercalcemia is due to excessive intestinal calcium absorption (vitamin D intoxication, granulomatous disorders, some lymphomas). Treatment reduces serum calcium and improves symptoms, at least transiently. The underlying cause of hypercalcemia should be identified and treated. The prognosis for asymptomatic PHPT is excellent with either medical or surgical management. Hypercalcemia of malignancy is associated with poor survival. CONCLUSIONS AND RELEVANCE Mild hypercalcemia is typically asymptomatic, while severe hypercalcemia is associated with nausea, vomiting, dehydration, confusion, somnolence, and coma. Asymptomatic hypercalcemia due to primary hyperparathyroidism is managed with parathyroidectomy or observation with monitoring, while severe hypercalcemia is typically treated with hydration and intravenous bisphosphonates.
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Affiliation(s)
- Marcella Donovan Walker
- Division of Endocrinology, Department of Medicine, Columbia University Irving Medical Center, Vagelos College of Physicians and Surgeons, New York, New York
| | - Elizabeth Shane
- Division of Endocrinology, Department of Medicine, Columbia University Irving Medical Center, Vagelos College of Physicians and Surgeons, New York, New York
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Pirklbauer M, Fuchs L, Heiss R, Ratschiller T, Mayer G. Intradialytic Calcium Kinetics and Cardiovascular Disease in Chronic Hemodialysis Patients. Blood Purif 2020; 49:723-732. [PMID: 32712610 PMCID: PMC7677992 DOI: 10.1159/000508060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 04/20/2020] [Indexed: 12/28/2022]
Abstract
BACKGROUND/OBJECTIVE Calcium loading has been associated with cardiovascular risk in hemodialysis (HD) patients. However, it remains to be elucidated whether alterations of intradialytic calcium buffering add to the increased cardiovascular disease burden in this high-risk population. METHODS Intradialytic calcium kinetics was evaluated in a cross-sectional observational study by measuring dialysate-sided ionized calcium mass balance (iCaMB), calcium buffer capacity, and change in serum calcium levels in 40 chronic HD patients during a routine HD session. A dialysate calcium of 3.5 mEq/L was used to adequately challenge calcium buffer mechanisms. Aortic pulse wave velocity and serum osteocalcin levels were measured prior to the HD session. Presence of cardiovascular disease and diabetes was assessed. RESULTS The mean dialysate-sided iCaMB, extracellular fluid ionized calcium mass gain, and buffered ionized calcium mass were 469 (±154), 111 (±49), and 358 (±145) mg/HD, respectively. The mean ionized serum calcium increase (∆iCa) was 0.42 (±0.14) mEq/L per HD. The mean intradialytic calcium buffer capacity was 73 (±18)%. Multivariate regression analysis revealed significant independent association of (1) iCaMB with the dialysate-to-blood calcium gradient at HD start and (2) intradialytic calcium buffer capacity with undercarboxylated osteocalcin. The presence of coronary heart disease was associated with higher ∆iCa but not iCaMB in the multivariate model. CONCLUSIONS In line with our proof-of-concept study, we provide clinical evidence for a rapidly accessible and exchangeable calcium pool involved in intradialytic calcium regulation and for the role of osteocalcin as a potential biomarker. Our findings argue for evaluating the prognostic potential of intradialytic calcium kinetics in prospective clinical trials.
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Affiliation(s)
- Markus Pirklbauer
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria,
| | - Lisa Fuchs
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
| | - Ramona Heiss
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
| | - Thomas Ratschiller
- Department of Cardiac, Vascular and Thoracic Surgery, Kepler University Hospital, Linz, Austria
| | - Gert Mayer
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
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Zheng R, Liu H, Gu J, Ni B, Sun H, Guo Y, Su C, He K, Du J, Shao Y. Upregulated microRNA‑330‑3p promotes calcification in the bicuspid aortic valve via targeting CREBBP. Mol Med Rep 2020; 22:2351-2363. [PMID: 32705274 PMCID: PMC7411470 DOI: 10.3892/mmr.2020.11297] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 05/01/2020] [Indexed: 01/21/2023] Open
Abstract
One key risk factor of aortic valve stenosis in clinical practice is bicuspid aortic valve (BAV). Increasing evidence indicates that numerous microRNAs (miRs/miRNAs) are involved in BAV calcification via their target genes. miR-330-3p was found to be involved in the deterioration of BAV calcification by miR profiling in human calcified BAV and tricuspid aortic valve (TAV) tissues in the present study and the underlying mechanism was investigated. RNA sequencing was performed on four BAV and four TAV tissues from patients with aortic stenosis before these leaflets were examined for the expression levels of miR-330-3p and CREB-binding protein (CREBBP) by reverse transcription-PCR. The alteration of functional factors associated with calcification was also assessed by Western blotting and immunohistochemistry in human aortic tissue samples. The putative target of miR-330-3p was detected by dual-luciferase assay in 293 cells. Furthermore, the influence of miR-330-3p expression on osteogenic progression was explored in cultured porcine valve interstitial cells (VICs). Rescue experiments of CRBBP were performed to confirm the influence of the miR-330-3p-CREBBP pathway in the calcification progress in porcine VICs. RNA sequencing indicated distinct expression of miR-330-3p in human BAV tissues compared with TAV, which was then confirmed by PCR. CREBBP expression levels in human BAV and TAV leaflets also demonstrated the opposite alterations. This negative correlation was then confirmed in cultured porcine VICs. Under an osteogenic environment, cellular calcification was promoted in miR-330-3p-overexpressed porcine VICs expressing higher bone morphogenetic protein 2, Runt-related transcription factor 2, matrix metalloproteinase (MMP)-2, MMP-9 and collagen I compared with controls. Rescue experiments further confirmed that miR-330-3p played its role via targeting CREBBP in porcine VICs. Collectively, miR-330-3p was upregulated in calcified BAV compared with TAV. The upregulation of miR-330-3p promotes the calcification progress partially via targeting CREBBP.
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Affiliation(s)
- Rui Zheng
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Hao Liu
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Jiaxi Gu
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Buqing Ni
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Haoliang Sun
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Yaojun Guo
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Chen Su
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Keshuai He
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Junjie Du
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
| | - Yongfeng Shao
- Department of Cardiovascular Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
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Dedic C, Hung TS, Shipley AM, Maeda A, Gardella T, Miller AL, Divieti Pajevic P, Kunkel JG, Rubinacci A. Calcium fluxes at the bone/plasma interface: Acute effects of parathyroid hormone (PTH) and targeted deletion of PTH/PTH-related peptide (PTHrP) receptor in the osteocytes. Bone 2018; 116:135-143. [PMID: 30053608 PMCID: PMC6158063 DOI: 10.1016/j.bone.2018.07.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 07/20/2018] [Accepted: 07/24/2018] [Indexed: 01/10/2023]
Abstract
Calcium ion concentration ([Ca2+]) in the systemic extracellular fluid, ECF-[Ca2+], is maintained around a genetically predetermined set-point, which combines the operational level of the kidney and bone/ECF interfaces. The ECF-[Ca2+] is maintained within a narrow oscillation range by the regulatory action of Parathyroid Hormone (PTH), Calcitonin, FGF-23, and 1,25(OH)2D3. This model implies two correction mechanisms, i.e. tubular Ca2+ reabsorption and osteoclast Ca2+ resorption. Although their alterations have an effect on the ECF-[Ca2+] maintenance, they cannot fully account for rapid correction of the continuing perturbations of plasma [Ca2+], which occur daily in life. The existence of Ca2+ fluxes at quiescent bone surfaces fulfills the role of a short-term error correction mechanism in Ca2+ homeostasis. To explore the hypothesis that PTH regulates the cell system responsible for the fast Ca2+ fluxes at the bone/ECF interface, we have performed direct real-time measurements of Ca2+ fluxes at the surface of ex-vivo metatarsal bones maintained in physiological conditions mimicking ECF, and exposed to PTH. To further characterize whether the PTH receptor on osteocytes is a critical component of the minute-to-minute ECF-[Ca2+] regulation, metatarsal bones from mice lacking the PTH receptor in these cells were tested ex vivo for rapid Ca2+ exchange. We performed direct real-time measurements of Ca2+ fluxes and concentration gradients by a scanning ion-selective electrode technique (SIET). To validate ex vivo measurements, we also evaluated acute calcemic response to PTH in vivo in mice lacking PTH receptors in osteocytes vs littermate controls. Our data demonstrated that Ca2+ fluxes at the bone-ECF interface in excised bones as well as acute calcemic response in the short-term were unaffected by PTH exposure and its signaling through its receptor in osteocytes. Rapid minute-to-minute regulation of the ECF-[Ca2+] was found to be independent of PTH actions on osteocytes. Similarly, mice lacking PTH receptor in osteocytes, responded to PTH challenge with similar calcemic increases.
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Affiliation(s)
- Christopher Dedic
- Molecular and Cell Biology, Goldman School of Dental Medicine, Boston University, Boston, MA, USA
| | - Tin Shing Hung
- Division of Life Sciences, State Key Laboratory for Molecular Neuroscience, HKUST, Hong Kong, China
| | | | - Akira Maeda
- Endocrine Unit, Massachusetts General Hospital, Boston, USA; Chugai Pharmaceutical, Japan
| | | | - Andrew L Miller
- Division of Life Sciences, State Key Laboratory for Molecular Neuroscience, HKUST, Hong Kong, China
| | - Paola Divieti Pajevic
- Molecular and Cell Biology, Goldman School of Dental Medicine, Boston University, Boston, MA, USA
| | - Joseph G Kunkel
- Pickus Center for Biomedical Research, University of New England, Biddeford, ME, USA
| | - Alessandro Rubinacci
- Bone Metabolism Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milano, Italy.
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Reinhard M, Frystyk J, Randers E, Bibby BM, Ivarsen P. Postprandial Mineral Handling in Patients on Maintenance Hemodialysis. J Ren Nutr 2018; 28:175-182. [PMID: 29429792 DOI: 10.1053/j.jrn.2017.11.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 11/02/2017] [Accepted: 11/19/2017] [Indexed: 11/11/2022] Open
Abstract
OBJECTIVE Patients on maintenance hemodialysis (HD) are unable to compensate for an enlarged mineral load with increased excretion of calcium and phosphate in the urine. Hence, excess calcium and phosphate must be neutralized by other mechanisms to avoid toxicity. The present study examined the acute handling of a mineral load in HD patients as compared with healthy subjects. DESIGN Controlled intervention study. SUBJECTS Twelve HD patients and 12 matched healthy subjects. INTERVENTION After a weight-adjusted standardized meal, blood samples were collected for the following 9 hours for ionized calcium, phosphate, parathyroid hormone (PTH), and fibroblast growth factor-23 (FGF23). The fractional excretion of calcium and phosphate was measured in controls. The patients were not allowed to take phosphate binders 24 hours before the experiment, and the study was performed on a non-HD day. RESULTS In healthy subjects, plasma calcium and phosphate did not change significantly from baseline, whereas HD patients demonstrated a decrease in plasma phosphate from 60 to 120 minutes by maximum 10% ([6; 13%], mean [95% confidence interval], P < .001) below baseline. PTH increased in both HD patients and controls and peaked 300 minutes after the meal 11% ([4; 19%], P < .004) above baseline in both groups. No changes in FGF23 were observed in HD patients, whereas FGF23 steadily decreased in controls, reaching nadir values at the end of the study 16% ([10; 21%], P < .001) below baseline. Control subjects demonstrated an immediate postprandial increase in the fractional excretion of both calcium and phosphate CONCLUSIONS: In HD patients, the mineral load paradoxically induced a decrease in plasma phosphate, whereas ionized calcium remained unchanged although PTH increased. These findings suggest that excess calcium and phosphate may be disposed of by mineral deposition, which may include soft tissue and vascular calcification.
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Affiliation(s)
- Mark Reinhard
- Department of Renal Medicine, Aarhus University Hospital, Aarhus, Denmark; Department of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus, Denmark.
| | - Jan Frystyk
- Medical Research Laboratory, Department of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus, Denmark
| | - Else Randers
- Department of Internal Medicine, Viborg Regional Hospital, Viborg, Denmark
| | - Bo Martin Bibby
- Department of Biostatistics, Aarhus University, Aarhus, Denmark
| | - Per Ivarsen
- Department of Renal Medicine, Aarhus University Hospital, Aarhus, Denmark; Department of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus, Denmark
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Granjon D, Bonny O, Edwards A. Coupling between phosphate and calcium homeostasis: a mathematical model. Am J Physiol Renal Physiol 2017; 313:F1181-F1199. [PMID: 28747359 DOI: 10.1152/ajprenal.00271.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/19/2017] [Accepted: 07/19/2017] [Indexed: 12/18/2022] Open
Abstract
We developed a mathematical model of calcium (Ca) and phosphate (PO4) homeostasis in the rat to elucidate the hormonal mechanisms that underlie the regulation of Ca and PO4 balance. The model represents the exchanges of Ca and PO4 between the intestine, plasma, kidneys, bone, and the intracellular compartment, and the formation of Ca-PO4-fetuin-A complexes. It accounts for the regulation of these fluxes by parathyroid hormone (PTH), vitamin D3, fibroblast growth factor 23, and Ca2+-sensing receptors. Our results suggest that the Ca and PO4 homeostatic systems are robust enough to handle small perturbations in the production rate of either PTH or vitamin D3 The model predicts that large perturbations in PTH or vitamin D3 synthesis have a greater impact on the plasma concentration of Ca2+ ([Ca2+]p) than on that of PO4 ([PO4]p); due to negative feedback loops, [PO4]p does not consistently increase when the production rate of PTH or vitamin D3 is decreased. Our results also suggest that, following a large PO4 infusion, the rapidly exchangeable pool in bone acts as a fast, transient storage PO4 compartment (on the order of minutes), whereas the intracellular pool is able to store greater amounts of PO4 over several hours. Moreover, a large PO4 infusion rapidly lowers [Ca2+]p owing to the formation of CaPO4 complexes. A large Ca infusion, however, has a small impact on [PO4]p, since a significant fraction of Ca binds to albumin. This mathematical model is the first to include all major regulatory factors of Ca and PO4 homeostasis.
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Affiliation(s)
- David Granjon
- Sorbonne Universités, UPMC University of Paris 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France.,Department of Pharmacology and Toxicology, University of Lausanne, and Service of Nephrology, Lausanne University Hospital, Lausanne, Switzerland; and
| | - Olivier Bonny
- Department of Pharmacology and Toxicology, University of Lausanne, and Service of Nephrology, Lausanne University Hospital, Lausanne, Switzerland; and
| | - Aurélie Edwards
- Sorbonne Universités, UPMC University of Paris 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France; .,Department of Biomedical Engineering, Boston University, Boston, Massachusetts
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Gubensek J, Orsag A, Ponikvar R, Buturovic-Ponikvar J. Calcium Mass Balance during Citrate Hemodialysis: A Randomized Controlled Trial Comparing Normal and Low Ionized Calcium Target Ranges. PLoS One 2016; 11:e0168593. [PMID: 28030601 PMCID: PMC5193410 DOI: 10.1371/journal.pone.0168593] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 11/30/2016] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Regional citrate anticoagulation (RCA) during hemodialysis interferes with calcium homeostasis. Optimal ionized calcium (iCa) target range during RCA and consequent calcium balance are unknown. METHODS In a randomized controlled trial (ACTRN12613001029785) 30 chronic hemodialysis patients were assigned to normal (1.1-1.2 mmol/) or low (0.95-1.05 mmol/l) iCa target range during a single hemodialysis with RCA. The primary outcome was calcium mass balance during the procedure, using a partial spent dialysate collection method; magnesium mass balance was also measured. Intact parathormone (iPTH), total calcium (tCa) and magnesium were measured before and after procedures. RESULTS Mean iCa during procedures was significantly different in the two groups (1.12±0.06 in normal and 1.06±0.07 mmol/l in low iCa group, p <0.001), resulting in different tCa (2.18±0.22 vs. 1.95±0.17, p = 0.003) after the procedure. Mean delivered calcium during the procedure was 58.3±4.8 mmol in the normal and 51.5±8.2 mmol in the low iCa group (p = 0.010), which resulted in a significantly higher mean positive calcium mass balance of 14.6±8.3 mmol (584±333 mg) per procedure in normal as compared to 7.2±8.5 mmol (290±341 mg) in low iCa group (p = 0.024). Linear mixed effects model showed a significant interaction effect of time and iCa target range group on iPTH, i.e. a significant increase in iPTH in the low as compared to normal iCa target group (p = 0.008). Magnesium mass balance was mildly negative and comparable in both groups. CONCLUSIONS Low iCa target range resulted in a significantly less positive calcium mass balance, but in a significant increase in iPTH. To achieve a more neutral calcium balance, we recommend allowing a mild hypocalcemia during hemodialysis with RCA, especially when it is used for prolonged periods.
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Affiliation(s)
- Jakob Gubensek
- Department of Nephrology, University Medical Centre Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- * E-mail:
| | - Alesa Orsag
- Department of Nephrology, University Medical Centre Ljubljana, Ljubljana, Slovenia
| | - Rafael Ponikvar
- Department of Nephrology, University Medical Centre Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Jadranka Buturovic-Ponikvar
- Department of Nephrology, University Medical Centre Ljubljana, Ljubljana, Slovenia
- Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
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Pirklbauer M, Schupart R, Mayer G. Acute calcium kinetics in haemodialysis patients. Eur J Clin Invest 2016; 46:976-984. [PMID: 27689678 DOI: 10.1111/eci.12680] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 09/27/2016] [Indexed: 12/21/2022]
Abstract
INTRODUCTION To avoid excessive calcium loading in haemodialysis (HD) patients, current guidelines suggest a dialysate calcium concentration (dCa) of 2·5 mEq/L based on relatively stable intradialytic serum calcium levels. However, the latter do not account for possible calcium storage in acutely accessible pools. A rapidly exchangeable calcium pool located at the bone level has been previously proposed to be involved in acute (minute-to-minute) extracellular calcium regulation. DESIGN To evaluate the contribution of this pool in the maintenance of serum calcium levels, acute calcium buffer capacity was assessed by measuring intradialytic dialysate-sided ionized calcium mass balance (iCaMB ) and change in extracellular fluid calcium mass in chronic HD patients using a dCa of 3·5 (n = 28) and 2·5 (n = 10) mEq/L. Serum osteocalcin, the most abundant noncollagenous bone protein, was measured before the HD session. RESULTS iCaMB was invariably positive for both 2·5 and 3·5 mEq/L dCa, with a mean of 434 (±125) and 725 (±162) mg/HD, respectively (P < 0·001). Buffered intradialytic calcium load was 410 (±116) and 565 (±130) mg/HD, and acute calcium buffer capacity was 95 (±8)% and 78 (±7)% (mean values at 2·5 and 3·5 mEq/L dCa, respectively) (P < 0·001). Using 3·5 mEq/L dCa, an independent association of acute calcium buffer capacity with undercarboxylated osteocalcin (β = 0·512, P = 0·002) was demonstrated. CONCLUSIONS Our data strongly suggest the existence of a rapidly exchangeable calcium pool that counteracts acute serum calcium deviations in HD patients. This study provides, for the first time, experimental evidence for the involvement of bone in acute extracellular calcium regulation in vivo.
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Affiliation(s)
- Markus Pirklbauer
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
| | - Ramona Schupart
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
| | - Gert Mayer
- Department of Internal Medicine IV - Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
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Alexander RT, Cordat E, Chambrey R, Dimke H, Eladari D. Acidosis and Urinary Calcium Excretion: Insights from Genetic Disorders. J Am Soc Nephrol 2016; 27:3511-3520. [PMID: 27468975 DOI: 10.1681/asn.2016030305] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone and inhibition of calcium transport processes within the renal tubule. The mechanisms whereby acid alters the integrity and stability of bone have been examined extensively in the published literature. Here, after briefly reviewing this literature, we consider the effects of acid on calcium transport in the renal tubule and then discuss why not all gene defects that cause renal tubular acidosis are associated with hypercalciuria and nephrocalcinosis.
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Affiliation(s)
- R Todd Alexander
- Departments of Pediatrics and .,Physiology, University of Alberta, Edmonton, Canada
| | | | - Régine Chambrey
- Institut National de la Santé et de la Recherche Médicale U970, Paris Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Demark; and
| | - Dominique Eladari
- Institut National de la Santé et de la Recherche Médicale U970, Paris Centre de Recherche Cardiovasculaire, Université Paris Descartes, Sorbonne Paris Cité, Paris, France.,Department of Physiologie, Hôpital Européen Georges Pompidou, Assistance Publique Hôpitaux de Paris, Paris, France
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Granjon D, Bonny O, Edwards A. A model of calcium homeostasis in the rat. Am J Physiol Renal Physiol 2016; 311:F1047-F1062. [PMID: 27358053 DOI: 10.1152/ajprenal.00230.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 06/27/2016] [Indexed: 12/14/2022] Open
Abstract
We developed a model of calcium homeostasis in the rat to better understand the impact of dysfunctions such as primary hyperparathyroidism and vitamin D deficiency on calcium balance. The model accounts for the regulation of calcium intestinal uptake, bone resorption, and renal reabsorption by parathyroid hormone (PTH), vitamin D3, and Ca2+ itself. It is the first such model to incorporate recent findings regarding the role of the calcium-sensing receptor (CaSR) in the kidney, the presence of a rapidly exchangeable pool in bone, and the delayed response of vitamin D3 synthesis. Accounting for two (fast and slow) calcium storage compartments in bone allows the model to properly predict the effects of bisphophonates on the plasma levels of Ca2+ ([Ca2+]p), PTH, and vitamin D3 Our model also suggests that Ca2+ exchange rates between plasma and the fast pool vary with both sex and age, allowing [Ca2+]p to remain constant in spite of sex- and age-based hormonal and other differences. Our results suggest that the inconstant hypercalciuria that is observed in primary hyperparathyroidism can be attributed in part to counterbalancing effects of PTH and CaSR in the kidney. Our model also correctly predicts that calcimimetic agents such as cinacalcet bring down [Ca2+]p to within its normal range in primary hyperparathyroidism. In addition, the model provides a simulation of CYP24A1 inactivation that leads to a situation reminiscent of infantile hypercalcemia. In summary, our model of calcium handling can be used to decipher the complex regulation of calcium homeostasis.
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Affiliation(s)
- David Granjon
- Sorbonne Universités, UPMC Univ Paris 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France; and.,Department of Pharmacology and Toxicology, University of Lausanne, and Service of Nephrology, Lausanne University Hospital, Lausanne, Switzerland
| | - Olivier Bonny
- Department of Pharmacology and Toxicology, University of Lausanne, and Service of Nephrology, Lausanne University Hospital, Lausanne, Switzerland
| | - Aurélie Edwards
- Sorbonne Universités, UPMC Univ Paris 06, Université Paris Descartes, Sorbonne Paris Cité, INSERM UMRS 1138, CNRS ERL 8228, Centre de Recherche des Cordeliers, Paris, France; and
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Muller ME, Forni Ogna V, Maillard M, Stoudmann C, Zweiacker C, Anex C, Wuerzner G, Burnier M, Bonny O. Furosemide stimulation of parathormone in humans: role of the calcium-sensing receptor and the renin-angiotensin system. Pflugers Arch 2015; 467:2413-21. [PMID: 26089029 DOI: 10.1007/s00424-015-1714-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 06/01/2015] [Accepted: 06/07/2015] [Indexed: 10/23/2022]
Abstract
Interactions between sodium and calcium regulating systems are poorly characterized but clinically important. Parathyroid hormone (PTH) levels are increased shortly after furosemide treatment by an unknown mechanism, and this effect is blunted by the previous administration of a calcimimetic in animal studies. Here, we explored further the possible underlying mechanisms of this observation in a randomized crossover placebo-controlled study performed in 18 human males. Volunteers took either cinacalcet (60 mg) or placebo and received a 20 mg furosemide injection 3 h later. Plasma samples were collected at 15-min intervals and analyzed for intact PTH, calcium, sodium, potassium, magnesium, phosphate, plasma renin activity (PRA), and aldosterone up to 6 h after furosemide injection. Urinary electrolyte excretion was also monitored. Subjects under placebo presented a sharp increase in PTH levels after furosemide injection. In the presence of cinacalcet, PTH levels were suppressed and marginal increase of PTH was observed. No significant changes in electrolytes and urinary excretion were identified that could explain the furosemide-induced increase in PTH levels. PRA and aldosterone were stimulated by furosemide injection but were not affected by previous cinacalcet ingestion. Expression of NKCC1, but not NKCC2, was found in parathyroid tissue. In conclusion, our results indicate that furosemide acutely stimulates PTH secretion in the absence of any detectable electrolyte changes in healthy adults. A possible direct effect of furosemide on parathyroid gland needs further studies.
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Affiliation(s)
- Marie-Eve Muller
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Valentina Forni Ogna
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Marc Maillard
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Candice Stoudmann
- Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland
| | - Carole Zweiacker
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Christiane Anex
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Grégoire Wuerzner
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Michel Burnier
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland
| | - Olivier Bonny
- Service of Nephrology and Hypertension, Department of Medicine, Lausanne University Hospital, Lausanne, Switzerland. .,Department of Pharmacology and Toxicology, University of Lausanne, Lausanne, Switzerland.
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Langote A, Ahearn M, Zimmerman D. Dialysate Calcium Concentration, Mineral Metabolism Disorders, and Cardiovascular Disease: Deciding the Hemodialysis Bath. Am J Kidney Dis 2015; 66:348-58. [PMID: 25958080 DOI: 10.1053/j.ajkd.2015.02.336] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 02/04/2015] [Indexed: 11/11/2022]
Abstract
Patients with end-stage kidney disease treated with dialysis are at increased risk to experience fractures and cardiovascular events than similar-aged people from the general population. The enhanced risk for these outcomes in dialysis patients is not completely explained by traditional risk factors for osteoporosis and cardiovascular disease. Mineral metabolism abnormalities are almost universal by the time patients require dialysis therapy, with most patients having some type of renal osteodystrophy and vascular calcification. These abnormalities have been linked to adverse skeletal and cardiovascular events. However, it has become clear that the treatment regimens used to modify the serum calcium, phosphate, and parathyroid hormone levels almost certainly contribute to the poor outcomes for dialysis patients. In this article, we focus on one aspect of mineral metabolism management; dialysate calcium concentration and the relationships among dialysate calcium concentrations, mineral and bone disorder, and cardiovascular disease in hemodialysis patients.
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Affiliation(s)
- Amit Langote
- Division of Nephrology, Department of Medicine, University of Ottawa, Ottawa Hospital, Ottawa, Ontario, Canada
| | - Micayla Ahearn
- Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Deborah Zimmerman
- Division of Nephrology, Department of Medicine, University of Ottawa, Ottawa Hospital, Ottawa, Ontario, Canada; Kidney Research Centre, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
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Hesse B, Varga P, Langer M, Pacureanu A, Schrof S, Männicke N, Suhonen H, Maurer P, Cloetens P, Peyrin F, Raum K. Canalicular network morphology is the major determinant of the spatial distribution of mass density in human bone tissue: evidence by means of synchrotron radiation phase-contrast nano-CT. J Bone Miner Res 2015; 30:346-56. [PMID: 25130720 DOI: 10.1002/jbmr.2324] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 07/24/2014] [Accepted: 07/29/2014] [Indexed: 11/11/2022]
Abstract
In bone remodeling, maturation of the newly formed osteonal tissue is associated with a rapid primary increase followed by a slower secondary increase of mineralization. This requires supply and precipitation of mineral into the bone matrix. Mineral delivery can occur only from the extracellular fluid via interfaces such as the Haversian system and the osteocyte pore network. We hypothesized that in mineralization, mineral exchange is achieved by the diffusion of mineral from the lacunar-canalicular network (LCN) to the bone matrix, resulting in a gradual change in tissue mineralization with respect to the distance from the pore-matrix interface. We expected to observe alterations in the mass density distribution with tissue age. We further hypothesized that mineral exchange occurs not only at the lacunar but also at the canalicular boundaries. The aim of this study was, therefore, to investigate the spatial distribution of mass density in the perilacunar and pericanalicular bone matrix and to explore how these densities are influenced by tissue aging. This is achieved by analyzing human jawbone specimens originating from four healthy donors and four treated with high-dosage bisphosphonate using synchrotron radiation phase-contrast nano-CT with a 50-nm voxel size. Our results provide the first experimental evidence that mass density in the direct vicinity of both lacunae (p < 0.001) and canaliculi (p < 0.001) is different from the mean matrix mass density, resulting in gradients with respect to the distance from both pore-matrix interfaces, which diminish with increasing tissue age. Though limited by the sample size, these findings support our hypotheses. Moreover, the density gradients are more pronounced around the lacunae than around the canaliculi, which are explained by geometrical considerations in the LCN morphology. In addition, we speculate that mineral exchange occurs at all interfaces of the LCN, not only in mineralization but also in mineral homeostasis.
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Affiliation(s)
- Bernhard Hesse
- European Synchrotron Radiation Facility, Grenoble, France; Berlin-Brandenburg School for Regenerative Therapies & Julius Wolff Institute, Charité, Universitätsmedizin Berlin, Berlin, Germany
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Cejka D, Weber M, Diarra D, Reiter T, Kainberger F, Haas M. Inverse association between bone microarchitecture assessed by HR-pQCT and coronary artery calcification in patients with end-stage renal disease. Bone 2014; 64:33-8. [PMID: 24709688 DOI: 10.1016/j.bone.2014.03.048] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Revised: 03/11/2014] [Accepted: 03/27/2014] [Indexed: 10/25/2022]
Abstract
It is a matter of debate whether vascular calcification and bone loss are simultaneously occurring but largely independent processes or whether poor bone health predisposes to vascular calcification, especially in patients with kidney disease. Here we investigated the association between the changes of microarchitecture in weight bearing bone and the extent of coronary artery calcification in patients with chronic renal failure. The bone microarchitecture of the tibia using high-resolution peripheral quantitative computed tomography (HR-pQCT), bone mineral density using dual X-ray absorptiometry (DXA) of the lumbar spine, femoral neck and distal radius as well as coronary artery calcification using multi-slice CT and reported as Agatston score were measured in 66 patients with end-stage renal disease on chronic hemodialysis. Markers of bone turnover, vitamin D status and intact parathyroid hormone (iPTH) were assessed. CAC score was found to be <100 in 39% and ≥100 in 61% of patients. The median [95% CI] total CAC score was 282 [315-2587]. By univariate analysis, significant correlations between CAC and age (R=0.52, p<0.001), weight (R=0.3, p<0.01) and serum cross laps (CTX, R=-0.39, p<0.01) were found, and parameters of bone microarchitecture were numerically but not significantly lower in patients with CAC scores ≥100. In multivariate analysis stratifying for gender and correcting for age, tibial density (Dtot) and bone volume/total volume (BV/TV) were significantly lower in patients with CAC scores ≥100 (p<0.05 for both). Low trabecular bone volume and decreased cortical bone density are associated with coronary artery calcification in dialysis patients.
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Affiliation(s)
- Daniel Cejka
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria; Medical University Vienna, Vienna, Austria.
| | - Michael Weber
- Medical University Vienna, Vienna, Austria; Department of Radiology, Medical University Vienna, Vienna, Austria.
| | - Danielle Diarra
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria; Medical University Vienna, Vienna, Austria.
| | - Thomas Reiter
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria; Medical University Vienna, Vienna, Austria.
| | - Franz Kainberger
- Medical University Vienna, Vienna, Austria; Division of Neuroradiology and Musculoskeletal Radiology, Department of Radiology, Medical University Vienna, Vienna, Austria.
| | - Martin Haas
- Division of Nephrology and Dialysis, Department of Medicine III, Medical University Vienna, Vienna, Austria; Medical University Vienna, Vienna, Austria.
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Whyte MP, Leelawattana R, Reinus WR, Yang C, Mumm S, Novack DV. Acute severe hypercalcemia after traumatic fractures and immobilization in hypophosphatasia complicated by chronic renal failure. J Clin Endocrinol Metab 2013; 98:4606-12. [PMID: 24064686 PMCID: PMC6287393 DOI: 10.1210/jc.2013-1811] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Hypophosphatasia (HPP) features deficient activity of the "tissue-nonspecific" isoenzyme of alkaline phosphatase (TNSALP) due to loss-of-function mutation(s) within the TNSALP gene. Consequently, inorganic pyrophosphate, a TNSALP substrate and inhibitor of mineralization, accumulates extracellularly. This can cause rickets or osteomalacia. OBJECTIVE We report a 55-year-old man with HPP and chronic renal failure (CRF) requiring hemodialysis who developed severe hypercalcemia acutely after traumatic fractures and immobilization. He manifested HPP in childhood and in middle age received hemodialysis for CRF attributed to hypertension and anti-inflammatory medication. He took 2 g of calcium carbonate orally each day to bind dietary phosphorus, but never aluminum hydroxide or any form of vitamin D. Pretrauma serum levels of calcium spanned 8.4-10.7 mg/dL (normal [Nl], 8.6-10.3), inorganic phosphate 5.8-6.4 mg/dL (Nl, 2.5-4.5), and PTH 63-75 pg/mL (Nl, 10-55). RESULTS Rapid succession falls fractured multiple major bones. Six hours later, he became confused. Serum calcium was 14.9 mg/dL, ionized calcium was 7.4 mg/dL (Nl, 4.5-5.1), and PTH was 16 pg/mL. Hemodialysis quickly corrected his hypercalcemia and confusion. Low serum alkaline phosphatase persisted, and follow-up skeletal histopathology showed that his osteomalacia was severe. CONCLUSION Hemodialysis does not heal the skeletal disease of HPP. During sudden fracture immobilization in HPP, sufficient calcium can emerge from bone, perhaps from a rapidly exchangeable calcium pool, to cause acute severe hypercalcemia if the kidneys cannot compensate for the mineral efflux. Hence, we worry that acute hypercalcemia might accompany sudden immobilization in CRF patients without HPP if they have adynamic bone disease.
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Affiliation(s)
- Michael P Whyte
- MD, Shriners Hospital for Children, 2001 South Lindbergh Boulevard, St Louis, MO 63131.
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Mattu M, Yarlagadda SG. Metastatic calcifications after parathyroidectomy in a dialysis patient. Nephrology (Carlton) 2013; 18:646-7. [PMID: 23980815 DOI: 10.1111/nep.12099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/08/2013] [Indexed: 11/26/2022]
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Abstract
The incidence of renal osteodystrophy (ROD) increases with deteriorating kidney function, affecting virtually every patient on chronic dialysis treatment. ROD can persist after kidney transplantation and may be aggravated by immunosuppressants, mainly glucocorticoids. Fracture risk, including hip fractures, is markedly elevated in patients with renal disease compared to the general population. Depending on the type of ROD, high or low bone turnover can be found. Because of poor positive and negative predictive values of serological markers of bone turnover and limited technical capabilities of various bone imaging modalities, the only reliable method to correctly classify ROD is the transiliac bone biopsy. Elevated bone turnover can be successfully treated with active vitamin D, cinacalcet, or parathyreoidectomy, but all of these therapies may lead to oversuppression of bone metabolism. Currently, no specific therapy is available for low turnover bone disease. Bisphosphonates can be a therapeutic option for selected patients after renal transplantation.
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