Secondary hyperparathyroidism: Predictors and relationship with vitamin D status, bone turnover markers and bone mineral density.

INTRODUCTION: Secondary hyperparathyroidism (SHPT) has adverse implications for bone health but is relatively understudied. In this study we examine the prevalence and determinants of SHPT and describe the relationship of SHPT with bone turnover markers and bone mineral density (BMD) in older Irish adults. METHOD: Eligible participants (n = 4139) were identified from the Trinity-Ulster-Department of Agriculture (TUDA) study, a cohort of Irish adults aged ≥60 years. Exclusion criteria included an estimated glomerular filtration rate (eGFR) <30 ml/min and serum calcium >2.5 mmol/l to remove hyperparathyroidism due to advanced chronic kidney disease (CKD) and primary hyperparathyroidism respectively. The relationship between SHPT and bone turnover markers and BMD (measured by densitometry) was examined in a subsample (n = 1488). Vitamin D deficiency was defined as 25-hydroxyvitamin D [25 (OH)D] <30 nmol/l. RESULTS: Participants had a mean age of 73.6 ± 7.9 years, 65.1 % were female and 19.4 % were found to be vitamin D deficient. The prevalence of SHPT decreased as vitamin D increased, from 30.6 % in those deficient to 9.8 % in those with 25(OH)D ≥ 50 nmol/l and increased with declining kidney function. In non­calcium supplement users, principal determinants of SHPT were vitamin D deficiency (OR 4.18, CI 3.05-5.73, p < 0.001), eGFR 30-44 ml/min (OR 3.69, CI 2.44-5.57, p < 0.001), loop diuretic use (OR 3.52, CI 2.59-4.79, p < 0.001) and to a lesser extent body mass index (p = 0.001), eGFR 45-59 ml/min (p < 0.001) and 25(OH)D level 30-49 nmol/l (p = 0.002). Similar findings were observed in calcium supplement users, though proton pump inhibitors were also associated with SHPT (OR 1.55, CI 1.08-2.22, p = 0.018) while vitamin D 30-49 nmol/l was not. In participants with SHPT versus those without, bone turnover markers were higher: bone alkaline phosphatase (p = 0.017) and tartrate-resistant acid phosphatase (p = 0.033), whilst there was lower BMD at the neck of femur (0.880 vs. 0.903 g/cm2, p = 0.033) and total hip (0.968 vs. 0.995 g/cm2, P = 0.017). DISCUSSION: The results show that up to one in six older Irish adults had SHPT and this was associated with lower BMD and higher concentrations of bone turnover markers. Both vitamin D deficiency and 25(OH)D level 30-49 nmol/l were important predictors of SHPT. Loop diuretics and PPIs may also increase the risk of SHPT, and their use may need to be carefully considered in this population. Further studies examining the potential impact of these factors on bone health in similar populations to our study sample are warranted.

The value of clinical-ultrasonographic feature model to predict the severity of secondary hyperparathyroidism.

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.

Activation of the Calcium Receptor by Calcimimetic Agents Is Preserved Despite Modest Attenuating Effects of Hyperphosphatemia.

BACKGROUND: Phosphorus levels in the range seen clinically among patients undergoing dialysis have been reported to attenuate calcium receptor activation and modify parathyroid hormone (PTH) release from isolated parathyroid glands in vitro. Some clinicians and providers of dialysis thus have suggested that calcimimetic agents are ineffective and should not be used to manage secondary hyperparathyroidism among those undergoing dialysis when serum phosphorus concentrations exceed certain threshold levels. METHODS: To determine whether hyperphosphatemia diminishes the therapeutic response to calcimimetic agents, we used data from large clinical trials to analyze the effects of etelcalcetide and cinacalcet to lower plasma PTH levels in individuals on hemodialysis who had secondary hyperparathyroidism and varying degrees of hyperphosphatemia. RESULTS: Plasma PTH levels declined progressively during 26 weeks of treatment with either etelcalcetide or cinacalcet without regard to the degree of hyperphosphatemia at baseline. However, with each calcimimetic agent, the decreases in PTH from baseline were less at each interval of follow-up during the trials among participants with serum phosphorus levels above one of three prespecified threshold values compared with those with serum phosphorus levels below these thresholds. CONCLUSIONS: These in vivo findings are the first in humans to support the idea that hyperphosphatemia attenuates calcium receptor activation by calcium ions and by calcimimetic agents. The effect of hyperphosphatemia on the responsiveness to calcimimetic agents appears relatively modest, however, and unlikely to be significant therapeutically. The efficacy of treatment with calcimimetic agents for lowering plasma PTH levels among those with secondary hyperparathyroidism remains robust despite substantial elevations in serum phosphorus.

Comparison between different sources of minerals in horses with nutritional secondary hyperparathyroidism / [Comparação entre diferentes fontes de minerais em cavalos com hiperparatireoidismo secundário nutricional]

Minerals perform several functions in the body, such as coagulation actions, muscle contraction, enzymatic and hormonal production, among others. This study aims to evaluate the effect of a 150 days chelated and not chelated mineral supplementation with and without potassium oxalate on serological parameters and bone mineral density of horses. Twenty-four crossbred yearlings (12 females and 12 males) with an average age of 21±3 months and body weight of 330.8±37.9kg were divided into four groups containing six equines in each (three females and three males) in a completely randomized design with repeated measurements in a 2x2 factorial arrangement. Treatments were: 1 - chelated minerals compound; 2 - chelated minerals compound and potassium oxalate; 3 - not chelated minerals compound; and 4 - not chelated minerals compound and potassium oxalate. Clinical signs of nutritional secondary hyperparathyroidism (NSH) were observed only in treatment 4. Results showed no treatment effect in bone biopsy for calcium, phosphorus and bone density. There were significant reductions of parathyroid hormone (PTH) means concentrations in treatments 2 and 4 during supplementation. Animals supplemented with chelated minerals compounds avoided mineral imbalances and NSH even when in dietary potassium oxalate challenged.(AU)

Os minerais desempenham diversas funções no organismo, como ações de coagulação, contração muscular, produção enzimática e hormonal, entre outras. O objetivo deste estudo foi avaliar o efeito da suplementação de minerais quelatados e não quelatados, por 150 dias, com e sem oxalato de potássio, sobre parâmetros sorológicos e densidade mineral óssea em equinos. Vinte e quatro filhotes mestiços (12 fêmeas e 12 machos), com idade média de 21±3 meses e peso corporal de 330,8±37,9kg, foram divididos em quatro grupos contendo seis equinos cada (três fêmeas e três machos), em delineamento inteiramente ao acaso, com repetição medida em arranjo fatorial 2x2. Os tratamentos foram: 1 - composto mineral quelatado; 2 - composto mineral quelatado e oxalato de potássio; 3 - composto mineral não quelatado; e 4 - composto mineral não quelatado e oxalato de potássio. Os sinais clínicos do hiperparatireoidismo secundário nutricional (NSH) foram observados apenas no tratamento 4. Os resultados não mostraram efeito de tratamento na biópsia óssea para cálcio, fósforo e densidade óssea. Houve redução significativa do hormônio da paratireoide (PTH) em concentrações médias nos tratamentos 2 e 4 durante a suplementação. Os animais suplementados com compostos minerais quelatados evitaram desequilíbrios minerais e NSH, mesmo quando desafiados no oxalato de potássio na dieta.(AU)

The risk of medically uncontrolled secondary hyperparathyroidism depends on parathyroid hormone levels at haemodialysis initiation.

BACKGROUND: Optimal parathyroid hormone (PTH) control during non-dialysis chronic kidney disease (ND-CKD) might decrease the subsequent risk of parathyroid hyperplasia and uncontrolled secondary hyperparathyroidism (SHPT) on dialysis. However, the evidence for recommending PTH targets and therapeutic strategies is weak for ND-CKD. We evaluated the patient characteristics, treatment patterns and PTH control over the first year of haemodialysis (HD) by PTH prior to HD initiation. METHODS: We studied 5683 incident HD patients from 21 countries in Dialysis Outcomes and Practice Patterns Study Phases 4-6 (2009-18). We stratified by PTH measured immediately prior to HD initiation and reported the monthly prescription prevalence of active vitamin D and calcimimetics over the first year of HD and risk of PTH >600 pg/mL after 9-12 months on HD. RESULTS: The 16% of patients with PTH >600 pg/mL prior to HD initiation were more likely to be prescribed active vitamin D and calcimimetics during the first year of HD. The prevalence of PTH >600 pg/mL 9-12 months after start of HD was greater for patients who initiated HD with PTH >600 (29%) versus 150-300 (7%) pg/mL (adjusted risk difference: 19%; 95% confidence interval : 15%, 23%). The patients with sustained PTH >600 pg/mL after 9-12 months on HD were younger, more likely to be black, and had higher serum phosphorus and estimated glomerular filtration rates at HD initiation. CONCLUSIONS: Increased PTH before HD start predicted a higher PTH level 9-12 months later, despite greater use of active vitamin D and calcimimetics. More targeted PTH control during ND-CKD may influence outcomes during HD, raising the need for PTH target guidelines in these patients.

[Cholecalciferol supplementation improves secondary hyperparathyroidism control in hemodialysis patients].

Introduction: Vitamin D deficiency is common among hemodialysis (HD) patients and is an important component in the pathogenesis of secondary hyperparathyroidism (SHPT). We herein report our experience on the impact of cholecalciferol supplementation on PTH levels in a group of HD patients. Patients and methods: We selected 122 HD patients. The main selection criteria were 25- hydroxyvitamin D (25(OH)D) levels ≤30 ng/mL and SHPT defined as PTH levels >300 pg/mL or PTH levels between 150-300 pg/mL during therapy with cinacalcet or paricalcitol. 82 patients agreed to receive cholecalciferol at the fixed dose of 25,000 IU per week orally for 12 months, while the remaining 40 represented the control group. The main endopoints of the study were the reduction in PTH levels ≥30% compared to baseline values and the increase of 25(OH)D levels to values >30 ng/mL. Results: At follow-up PTH levels decreased in the supplemented group from 476 ±293 to 296 ± 207 pg/mL (p<0.001), 25(OH)D levels increased from 10.3 ± 5.7 to 33.5 ± 11.2 ng/mL (p<0.001), serum calcium increased from 8.6 ± 0.5 to 8.8 ± 0.6 mg/dL (p<0.05) while serum phosphorus did not change. In this group the mean doses of paricalcitol were significantly reduced, from 8.7 ± 4.0 to 6.1 ± 3.9 µg/week (p<0.001). Moreover, in this group there were a significant increase of hemoglobin levels, from 11.6 ± 1.3 to 12.2 ± 1.1 g/dL (p <0.01) and a significant reduction of erythropoietin doses (p<0.05). In the control group the 25(OH)D and PTH levels did not change, while cinacalcet doses increased from 21 ±14 to 43 ± 17 mg/d (p<0.01). Conclusions: Vitamin deficiency is very common in HD patients. Cholecalciferol treatment significantly increased serum 25(OH)D levels, significantly decreased PTH levels and paricalcitol doses, concurrently entailing a better control of anemia.

Development of evocalcet for unmet needs among calcimimetic agents.

INTRODUCTION: The calcium-sensing receptor is an important treatment target for secondary hyperparathyroidism (SHPT) in patients undergoing dialysis. In addition to vitamin D receptor activator, cinacalcet has recently been widely used for SHPT management, and the significant suppression of parathyroid hormone (PTH) with better control of serum calcium and phosphorus has been reported. However, low adherence and insufficient dose escalation mainly due to frequent gastrointestinal adverse events, still remain as major issues. To overcome these unmet needs, we have developed a new oral calcimimetic agent evocalcet, which has recently been approved by the Pharmaceutical Affairs Act in Japan. AREAS COVERED: PubMed was searched from inception until April 2020 with the word evocalcet to summarize the development of this new calcimimetic agent, its pharmacokinetics, and the results of clinical trials, along with an overview of the differences among calcimimetic agents. This review also includes the management of SHPT with a focus on calcimimetics. EXPERT OPINION: Evocalcet evoked fewer gastrointestinal-related adverse events while suppressing PTH at a lower dose than cinacalcet. These data suggest evocalcet may contribute to better adherence and sufficient dose escalation in patients with SHPT. Whether or not evocalcet improves clinical outcomes remains to be elucidated.

Biochemical spectrum of parathyroid disorders diagnosed at a tertiary care setting.

OBJECTIVE: To determine the clinical and biochemical pattern of parathyroid disorders in a tertiary care setting.. METHODS: The cross-sectional study was conducted at the Armed Forces Institute of Pathology, Rawalpindi, Pakistan, from September 2017 to February 2018, and comprised patients with suspected parathyroid disorders. A panel of biochemical tests were used for diagnosis of parathyroid disorders, which included parathyroid hormone levels, total calcium, ionized calcium, inorganic phosphorus, alkaline phosphatase, magnesium, total vitamin D and urinary calcium-to-creatinine ratio. SPSS 24 was used for data analysis. RESULTS: Of the 384 subjects, 248(65%) were male and 136(35%) were female. Overall mean age was 48±19years. Of the total, 302(786%) had parathyroid issues, with 244(81%) having secondary hyperparathyroidism. Mean serum total calcium, phosphorus, ionized calcium, magnesium and total vitamin D were 8.98±1.52 mg/dl, 4.0±1.30 mg/dl, 4.65±0.52 mg/dl, 2.11±0.27 mg/dl and 20.5±8.52 ngml respectively. Of the patients diagnosed with secondary hyperparathyroidism, 72.2% patients had chronic kidney disease and 20.2% had isolated vitamin D deficiency. CONCLUSIONS: Parathyroid disorders had significant impact on bone health. Moreover, secondary hyperparathyroidism was seen to be emerging as a major endocrine problem, especially in chronic kidney disease patients and vitamin D-deficient individuals.

Osteocalcin is an Independent Predictor for Hungry Bone Syndrome After Parathyroidectomy.

BACKGROUND: Hungry bone syndrome is characterized by prolonged and severe hypocalcemia following parathyroidectomy. Previously, we reported that preoperative alkaline phosphatase is a major factor predicting prolonged hospital stay. Nonetheless, some patients with low alkaline phosphatase levels presented with hungry bone syndrome, suggesting that additional factors may play a role. METHODS: From September 2010 to December 2017, consecutive dialysis patients who underwent parathyroidectomy for secondary hyperparathyroidism were analyzed. Length of hospital stay was used as a surrogate marker for postoperative bone hunger. RESULTS: A total of 260 patients were included in the study. The median postoperative hospital stay was 3 days, and 69 (27%) patients had a stay longer than 3 days. Multivariate logistic regression analysis revealed that alkaline phosphatase (odds ratio [OR] = 1.005), osteocalcin (OR = 1.001), and subtotal parathyroidectomy (OR = 0.061) were associated with prolonged hospital stay. Multivariate linear regression analysis indicated that age (ß = - 0.170), alkaline phosphatase (ß = 0.430), and osteocalcin (ß = 0.166) were correlated with the length of stay. After surgery, the median osteocalcin level increased from 264 to 478 ng/mL (P < 0.001). CONCLUSIONS: Alkaline phosphatase is the main predictor of hungry bone syndrome after parathyroidectomy, and preoperative osteocalcin is an additional independent predictor. Patients with a high osteocalcin level may prone to have a higher demand for calcium supplementation.

Evaluation of laboratory parameters and symptoms after parathyroidectomy in dialysis patients with secondary hyperparathyroidism.

Objectives: The aim of the study was to evaluate the laboratory parameters and symptoms after parathyroidectomy (PTX) in dialysis patients with secondary hyperparathyroidism (SHPT), and to briefly analyze the different therapeutic effects of the three surgical methods. Methods: A total of 182 dialysis patients who underwent PTX between February 2012 and January 2018 at the Second Affiliated Hospital of Soochow University were included in this study and followed for 12 months. Laboratory parameters such as calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), and intact parathyroid hormone (iPTH) were measured before and after operation. According to the follow-up time and type of operation, we calculated the percentage of laboratory indicators reaching the recommended range of the KDIGO guidelines after surgery. We also analyzed the improvement of bone pain and pruritus, as well as surgical complications. Results: After the operation, the levels of iPTH, Ca, and P decreased significantly at each time point. ALP increased at the first postoperative week and gradually decreased to normal range after 3 months. Symptoms, such as bone pain and pruritus, were significantly relieved. According to the follow-up time and three surgical methods (subtotal parathyroidectomy, total parathyroidectomy, total parathyroidectomy plus autologous transplantation), we found that the ratio of each laboratory parameter reaching the recommended range of KDIGO guidelines was significantly different. Conclusion: PTX is a safe and effective therapy for treating SHPT that is refractory to medical therapies and accompanied by related signs and symptoms in dialysis patients. All three operative techniques were effective in controlling SHPT.

The impact of cinacalcet in the mineral metabolism markers of patients on dialysis with severe secondary hyperparathyroidism / Impacto de cinacalcete em marcadores do metabolismo mineral de pacientes em diálise portadores de hiperparatireoidismo secundário grave

Abstract Introduction: Treating secondary hyperparathyroidism (SHPT), a common condition associated with death in patients with chronic kidney disease, is a challenge for nephrologists. Calcimimetics have allowed the introduction of drug therapies no longer based on phosphate binders and active vitamin D. This study aimed to assess the safety and effectiveness of cinacalcet in managing chronic dialysis patients with severe SHPT. Methods: This retrospective study included 26 patients [age: 52 ± 12 years; 55% females; time on dialysis: 54 (4-236) months] on hemodialysis (N = 18) or peritoneal dialysis (N = 8) with severe SHPT (intact parathyroid hormone (iPTH) level > 600 pg/mL) and hyperphosphatemia and/or persistent hypercalcemia treated with cinacalcet. The patients were followed for 12 months. Their serum calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), and iPTH levels were measured at baseline and on days 30, 60, 90, 180, and 365. Results: Patients with hyperphosphatemia (57.7%), hypercalcemia (23%), or both (19.3%) with iPTH > 600 pg/mL were prescribed cinacalcet. At the end of the study, decreases were observed in iPTH (1348 ± 422 vs. 440 ± 210 pg/mL; p < 0.001), Ca (9.5 ± 1.0 vs. 9.1 ± 0.6 mg/dl; p = 0.004), P (6.0 ± 1.3 vs. 4.9 ± 1.1 mg/dl; p < 0.001), and ALP (202 ± 135 vs. 155 ± 109 IU/L; p = 0.006) levels. Adverse events included hypocalcemia (26%) and digestive problems (23%). At the end of the study, 73% of the patients were on active vitamin D and cinacalcet. Three (11.5%) patients on peritoneal dialysis did not respond to therapy with cinacalcet, and their iPTH levels were never below 800 pg/mL. Conclusion: Cinacalcet combined with traditional therapy proved safe and effective and helped manage the mineral metabolism of patients with severe SHPT.

Resumo Introdução: O tratamento do hiperparatireoidismo secundário (HPTs), patologia comum e associada à mortalidade na doença renal crônica, é um desafio para o nefrologista. Advento dos calcimiméticos propiciou terapêutica medicamentosa diferente da usual, baseada em quelantes de fósforo e vitamina D ativa. O objetivo deste estudo foi avaliar segurança e efetividade de cinacalcete no controle do HPTs grave de pacientes em diálise crônica. Métodos: Estudo retrospectivo 26 pacientes [idade: 52 ± 12 anos; 55% mulheres; tempo em diálise: 54 (4-236) meses], em hemodiálise (N = 18) ou diálise peritoneal (N = 8), com HPTs grave (nível de paratormônio intacto (PTHi) > 600 pg/mL), com hiperfosfatemia e/ou hipercalcemia persistentes, em tratamento com cinacalcete. Período de seguimento de 12 meses. Avaliados níveis séricos de cálcio (Ca), fósforo (P), fosfatase alcalina (FA) e PTHi no início do seguimento, 30, 60, 90, 180 e 365 dias. Resultados: Indicações para início do cinacalcete: hiperfosfatemia (57,7%), hipercalcemia (23%), ou ambos (19,3%) com PTH > 600 pg/mL. Ao final do seguimento, observada redução dos níveis PTHi (1348 ± 422 vs. 440 ± 210 pg/mL; p < 0,001), Ca (9,5 ± 1,0 vs. 9,1 ± 0,6 mg/dl; p = 0,004), P (6,0 ± 1,3 vs. 4,9 ± 1,1 mg/dl; p < 0,001) e FA (202 ± 135 vs. 155 ± 109 UI/L; p = 0,006). Eventos adversos: hipocalcemia (26%) e queixas digestivas (23%). No fim do estudo, 73% pacientes utilizavam vitamina D ativada associada ao cinacalcete. Três (11,5%) pacientes, todos em DP, não responderam ao cinacalcete, mantendo níveis PTHi > 800 pg/mL. Conclusão: Utilização de cinacalcete, associado à terapia tradicional, em pacientes com HPTs grave foi segura, eficiente e associada a melhor controle do metabolismo mineral.

The impact of cinacalcet in the mineral metabolism markers of patients on dialysis with severe secondary hyperparathyroidism.

INTRODUCTION: Treating secondary hyperparathyroidism (SHPT), a common condition associated with death in patients with chronic kidney disease, is a challenge for nephrologists. Calcimimetics have allowed the introduction of drug therapies no longer based on phosphate binders and active vitamin D. This study aimed to assess the safety and effectiveness of cinacalcet in managing chronic dialysis patients with severe SHPT. METHODS: This retrospective study included 26 patients [age: 52 ± 12 years; 55% females; time on dialysis: 54 (4-236) months] on hemodialysis (N = 18) or peritoneal dialysis (N = 8) with severe SHPT (intact parathyroid hormone (iPTH) level > 600 pg/mL) and hyperphosphatemia and/or persistent hypercalcemia treated with cinacalcet. The patients were followed for 12 months. Their serum calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), and iPTH levels were measured at baseline and on days 30, 60, 90, 180, and 365. RESULTS: Patients with hyperphosphatemia (57.7%), hypercalcemia (23%), or both (19.3%) with iPTH > 600 pg/mL were prescribed cinacalcet. At the end of the study, decreases were observed in iPTH (1348 ± 422 vs. 440 ± 210 pg/mL; p < 0.001), Ca (9.5 ± 1.0 vs. 9.1 ± 0.6 mg/dl; p = 0.004), P (6.0 ± 1.3 vs. 4.9 ± 1.1 mg/dl; p < 0.001), and ALP (202 ± 135 vs. 155 ± 109 IU/L; p = 0.006) levels. Adverse events included hypocalcemia (26%) and digestive problems (23%). At the end of the study, 73% of the patients were on active vitamin D and cinacalcet. Three (11.5%) patients on peritoneal dialysis did not respond to therapy with cinacalcet, and their iPTH levels were never below 800 pg/mL. CONCLUSION: Cinacalcet combined with traditional therapy proved safe and effective and helped manage the mineral metabolism of patients with severe SHPT.

Treatment of secondary hyperparathyroidism with paricalcitol in patients with end-stage renal disease undergoing hemodialysis in Turkey: an observational study.

OBJECTIVE: To evaluate monthly percentage changes of intact parathyroid hormone (iPTH) and other major bone marker levels in patients with secondary hyperparathyroidism (SHPT) undergoing hemodialysis (HD) and receiving paricalcitol. METHODS: A total of 493 (F/M 244/249) adult patients with SHPT who were undergoing HD in 22 HD units and receiving paricalcitol treatment, with iPTH > 300 mg/mL, adjusted serum levels of calcium (Ca) < 10.2 mg/dL, and serum levels of inorganic phosphorus (iP) < 6 mg/dL were included in this multi-center, national, prospective, observational study. Data regarding efficacy, safety, and adverse events of paricalcitol treatment were collected during a 12-month follow-up period through monthly visits along with serum iPTH, Ca, iP, alkaline phosphatase (ALP) and other required biochemistry tests as necessary. Mortality data until 6 months after the end of the study were also investigated. RESULTS: The mean age was 58.3 ± 15.8 years and the mean duration of HD was 6.2 ± 5.5 years, respectively. As of 12th month, mean iPTH values decreased from 646 ± 424 pg/mL to 473 ± 387 pg/mL (p < 0.001); no statistically significant changes were observed in Ca levels (p > 0.05). Serum ALP levels also significantly decreased (p = 0.001) and serum phosphorus levels significantly increased (p < 0.001) during the study observation period. Reasons for early terminations were being lost to follow-up (n = 119, 24.1%), hyperphosphatemia (iP > 6 mg/dL, n = 108, 21.9%), low iPTH levels (iPTH < 150 mg/dL, n = 97, 19.7%), and withdrawal of consent (n = 41, 8.3%). In total 32 patients (6.5%) were prematurely terminated the study with hypercalcemia (Ca > 10.2 mg/dL). 46.9% of those hypercalcemic patients had other anomalies with iP and iPTH levels along with hypercalcemia. CONCLUSION: Paricalcitol treatment, resulted in successful iPTH control. In approximately 6.5% of the patients paricalcitol treatment was discontinued since Ca levels reached > 10.2 mg/dL in those patients. No unfavorable effects on serum phosphorus and Ca-phosphorus (Ca × P) product were observed.

Parathyroid Hormone and Cardiac Electrophysiology: A Review.

Calcium has long been known to be essential to cardiac electrical activity. Parathyroid hormone (PTH) is the main regulator of serum calcium and is central to calcium homeostasis. Although there are significant data linking parathyroid disease states with changes in cardiac electrophysiology, most data have focused on how PTH modulates serum calcium to produce these effects. Close scrutiny of early literature demonstrates that the relationship between PTH and electrocardiographic changes is not straightforward, and numerous studies have linked PTH to arrhythmia. Basic science research has demonstrated that there is a basis for a direct role of PTH on cardiac electrophysiology outside of its effect on serum calcium. Later studies in secondary hyperparathyroidism indicate that PTH disturbances could have important implications for broad categories of patients with cardiovascular disease. The current review summarizes the existing literature on PTH and electrophysiology based on clinical and basic science studies of various parathyroid states, providing directions for future study.

Calcium and Vitamin D Supplementation. Myths and Realities with Regard to Cardiovascular Risk.

Vitamin D and calcium are considered crucial for the treatment of bone diseases. Both vitamin D and calcium contribute to bone homeostasis but also preserve muscle health by reducing the risk of falls and fractures. Low vitamin D concentrations result in secondary hyperparathyroidism and contribute to bone loss, although the development of secondary hyperparathyroidism varies, even in patients with severe vitamin D deficiency. Findings from observational studies have shown controversial results regarding the association between bone mineral density and vitamin D/calcium status, thus sparking a debate regarding optimum concentrations of 25-hydroxyvitamin D and calcium for the best possible skeletal health. Although most of the intervention studies reported a positive effect of supplementation with calcium and vitamin D on bone in patients with osteoporosis, this therapeutic approach has been a matter of debate regarding potential side effects on the cardiovascular (CV) system. Thus, the aim of this review is to consider the current evidence on the physiological role of vitamin D and calcium on bone and muscle health. Moreover, we provide an overview on observational and interventional studies that investigate the effect of vitamin D and calcium supplementation on bone health, also taking into account the possible CV side-effects. We also provide molecular insights on the effect of calcium plus vitamin D on the CV system.

The effectiveness of cinacalcet: a randomized, open label study in chronic hemodialysis patients with severe secondary hyperparathyroidism.

BACKGROUND: Secondary hyperparathyroidism (SHPT) is associated with high incidences of cardiovascular disease, bone fracture, and mortality. This study was conducted to demonstrate the effectiveness of cinacalcet treatment on chronic kidney disease-mineral bone disorder (CKD-MBD) markers in chronic hemodialysis patients with severe SHPT. METHODS: In phase 1, 30 adult HD patients were randomized to cinacalcet or control groups for 12 weeks to explore the achievement of >30% reduction of iPTH. In phase 2, 45 patients were participated to further explore the effect of cinacalcet on CKD-MBD parameters for 24-week follow up and 12 additional weeks after cinacalcet discontinuation. RESULTS: In phase 1, the baseline serum iPTH levels were not different [1374 (955, 1639) pg/mL in the control group vs. 1191 (1005, 1884) pg/mL in the cinacalcet group], the percentage of patients achieving iPTH target were significantly higher in the treatment group [80% vs. 13%, p = .001]. In phase 2, the significant reductions of iPTH, FGF-23, tartrate-resistant acid phosphatase 5b, and slightly decreased size of parathyroid gland and stabilized vascular calcification were observed at 24-week follow up and markedly rebounded after discontinuation of cinacalcet. CONCLUSIONS: The effectiveness of cinacalcet were still obviously demonstrated even in chronic HD patients with severe SHPT. In addition, the improvements of bone markers and FGF-23, and stabilization of vascular calcification were observed. Therefore, cinacalcet can provide salutary effects on CKD-MBD in severe SHPT and might be an initially effective PTH-lowering therapy prior to surgical parathyroidectomy as well as an alternative treatment in the patients unsuitable for surgery. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov: NCT02056730. Date of registration: February 4, 2014.

Impact of three different daily doses of vitamin D3 supplementation in healthy schoolchildren and adolescents from North India: a single-blind prospective randomised clinical trial.

In India, there is a lack of information about the adequate daily dose of vitamin D3 supplementation in school children. Hence, we undertook this study to evaluate the adequacy and efficacy of different doses of vitamin D3 in schoolchildren. A total of 1008 vitamin D-deficient (VDD) children, aged 6-16 years with serum 25-hydroxyvitamin D (25(OH)D) levels <50nmol/l, were cluster randomised into three groups (A-344, B-341 and C-232) for supplementation (600, 1000 and 2000 IU daily) of vitamin D3 under supervision for 6 months. Of the 1008 subjects who completed the study, 938 (93 %) were compliant. Baseline and post-supplementation fasting blood and urine samples were evaluated for Ca, phosphates, alkaline phosphatase, 25(OH)D and parathormone and urine Ca:creatinine ratio. The mean age of the subjects was 11·7 (sd 2·4) years, and the overall mean baseline serum 25(OH)D level was 24·3 (SD 9·5)nmol/l. Post-supplementation rise in serum 25(OH)D in compliant group was maximum with 2000 IU (70·0 (SD 30·0)nmol/l), followed by 1000 IU (46·8 (SD 22·5)nmol/l) and 600 IU (36·5 (SD 18·5)nmol/l), and serum 25(OH)D levels of ≥50nmol/l were achieved in 71·5, 81·8 and 92·9 % by groups A, B and C, respectively. Secondary hyperparathyroidism decreased from 31·7 to 8·4 % post-supplementation. Two participants developed hypercalciuria, but none developed hypercalcaemia. Children with VDD benefit maximum with the daily supplementation of 2000 IU of vitamin D3. Whether recommendations of 400 IU/d by Indian Council of Medical Research or 600 IU by Indian Academy of Pediatrics or Institute of Medicine would suffice to achieve vitamin D sufficiency in children with VDD remains debatable.

Sevelamer hydrochloride suppresses proliferation of parathyroid cells during the early phase of chronic renal failure in rats.

AIM: We examined the effects of sevelamer on parathyroid cell proliferation and secondary hyperparathyroidism in rats following induction of early-phase of chronic renal failure (CRF) by unilateral ureteral obstruction (UUO). METHODS: For 5 days, rats in the control group received normal food, rats in the sevelamer group (SH) received control food plus 5% sevelamer, and rats in the low protein group (LP) received low protein food. Five rats of each group were killed at baseline (day 0). All other rats were given UUO, and five rats per group were killed on days 3, 7, 14, and 28 after UUO. Changes in body weight, serum phosphorus, calcium, intact-parathyroid hormone (i-PTH), creatinine (SCr), creatinine clearance rate (CCR), blood urea nitrogen (BUN), and 24-h urinary phosphorus were determined. Parathyroid tissues were removed for histological examination of proliferating cell nuclear antigen-positive (PCNA+) cells. RESULTS: Measurement of body weight, BUN, and SCr in the controls indicated successful establishment of this model of early-phase CRF. The controls also had remarkable proliferation of PCNA+ cells beginning on day 3, but this did not occur in the SH or LP groups. After 28 days, serum phosphorus had decreased more in the SH and LP groups than in the control group, and phosphorus excretion was much greater in the control group than in the SH and LP groups. The three groups had similar increases in serum i-PTH. CONCLUSION: Sevelamer rapidly lowered the serum phosphorus and inhibited the proliferation of PCNA+ cells in this experimental model of early-phase CRF.

Bone Microstructure in Response to Vitamin D3 Supplementation: A Randomized Placebo-Controlled Trial.

Vitamin D supplementation is often used in the prevention and treatment of osteoporosis, but the role of vitamin D has lately been questioned. We aimed to investigate the effect of 3 months of daily vitamin D3 supplementation (70 µg [2800 IU] vs. placebo) initiated in winter months on bone health. This study is a double-blinded placebo-controlled randomized trial. Bone health was assessed by bone turnover markers, DXA, HRpQCT, and QCT scans. The participants were 81 healthy postmenopausal women with low 25(OH)D (< 50 nmol/l) and high PTH levels (> 6.9 pmol/l) at screening. Vitamin D3 supplementation significantly increased levels of 25(OH)D and 1,25(OH)2D by 59 nmol/l and 19 pmol/l, respectively, whereas PTH was reduced by 0.7 pmol/l (all p < 0.0001). Compared with placebo, vitamin D3 did not affect bone turnover markers, aBMD by DXA or trabecular bone score. Vitamin D3 increased trabecular vBMD (QCT scans) in the trochanter region (0.4 vs. - 0.7 g/cm3) and the femoral neck (2.1 vs. - 1.8 g/cm3) pall < 0.05. HRpQCT scans of the distal tibia showed reduced trabecular number (- 0.03 vs. 0.05 mm-1) and increased trabecular thickness (0.001 vs. - 0.005 mm), as well as an improved estimated bone strength as assessed by failure load (0.1 vs. - 0.1 kN), and stiffness (2.3 vs. - 3.1 kN/mm pall ≤ 0.01). Changes in 25(OH)D correlated significantly with changes in trabecular thickness, stiffness, and failure load. Three months of vitamin D3 supplementation improved bone strength and trabecular thickness in tibia, vBMD in the trochanter and femoral neck, but did not affect aBMD.