A randomized study evaluating cinacalcet to treat hypercalcemia in renal transplant recipients with persistent hyperparathyroidism

Bridging the Gap Between CKD Management Paradigms in Transplant and Nontransplant Settings: Published Evidence, Challenges, and Perspectives

Kidney transplantation (KT) is the best treatment for patients with kidney failure, associated with improved survival and quality of life compared with maintenance dialysis. However, despite constant improvements in the assessment and management of the alloimmune response, KT patients frequently demonstrate a reduced estimated glomerular filtration rate. Therefore, the usual complications of chronic kidney disease (CKD), such as anemia, hypertension, metabolic acidosis, hyperkalemia, or persistent secondary hyperparathyroidism, are highly prevalent after KT. However, their underlying mechanisms are different in the transplant setting (compared with the nontransplanted CKD population), and management recommendations are based on relatively poor-quality data. In recent years, new therapies have emerged, significantly improving kidney and cardiovascular outcomes of non-KT patients with CKD. Whether those new drugs could improve the outcomes of KT patients has largely been under investigated so far. In this review, we will address the challenges of the management of a KT patient with a reduced estimated glomerular filtration rate, cover the published evidence, and highlight the critical knowledge gaps.

Chronic kidney disease-mineral and bone disorder: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference

In 2017, Kidney Disease: Improving Global Outcomes (KDIGO) published a Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD). Since then, new lines of evidence have been published related to evaluating disordered mineral metabolism and bone quality and turnover, identifying and inhibiting vascular calcification, targeting vitamin D levels, and regulating parathyroid hormone. For an in-depth consideration of the new insights, in October 2023, KDIGO held a Controversies Conference on CKD-MBD: Progress and Knowledge Gaps Toward Personalizing Care. Participants concluded that the recommendations in the 2017 CKD-MBD guideline remained largely consistent with the available evidence. However, the framework of the 2017 Guideline, with 3 major sections-biochemical abnormalities in mineral metabolism; bone disease; and vascular calcification-may no longer best reflect currently available evidence related to diagnosis and treatment. Instead, future guideline efforts could consider mineral homeostasis and deranged endocrine systems in adults within a context of 2 clinical syndromes: CKD-associated osteoporosis, encompassing increased fracture risk in patients with CKD; and CKD-associated cardiovascular disease, including vascular calcification and structural abnormalities, such as valvular calcification and left ventricular hypertrophy. Participants emphasized that the complexity of bone and cardiovascular manifestations of CKD-MBD necessitates personalized approaches to management.

Bisphosphonate therapy for persistent hyperparathyroidism after kidney transplantation-A case report

Post-transplant hyperparathyroidism (PT-HPT) is common in kidney transplant recipients (KTRs) and can cause nephrocalcinosis and graft dysfunction. Cinacalcet is commonly used for treating PT-HPT but may induce calciuria and exacerbate nephrocalcinosis. The concurrent use of bisphosphonates with cinacalcet to prevent this complication has not been reported. We report a case of PT-HPT-associated graft dysfunction. The patient had ESRD due to IgAN. She had been on continuous ambulatory peritoneal dialysis (CAPD) for 7 years before undergoing kidney transplantation (KT). Pre-KT intact parathyroid hormone (iPTH) was 101 pmol/L, alkaline phosphatase (ALP) 205 IU/L, Ca 2.40 mmol/L and PO4 2.2 mmol/L. There was immediate graft function after KT and the existence of persistent hyperparathyroidism (Cr 72 μmol/L, eGFR > 60 mL/min/1.73 m2, Ca 2.85 mmol/L, PO4 0.6 mmol/L, ALP 315 IU/L, iPTH 16.4 pmol/L). Progressive renal impairment ensued over the next 10 months (Cr 146 μmol/L, eGFR 34 mL/min/1.73 m2, Ca 2.77 mmol/L, PO4 0.9 mmol/L, ALP 142 IU/L, iPTH 24.4 pmol/L). Graft biopsy at 10 months post-KT revealed widespread tubular calcifications and no evidence of rejection. Intravenous pamidronate 60 mg was given quarterly for 3 doses in addition to cinacalcet therapy. ALP decreased from 147 to 81 IU/L despite refractory PT-HPT and renal function improved. Total parathyroidectomy was performed 1 month after the last pamidronate dose. Renal function remained stable for up to 4 years post-KT (Cr 151 μmol/L, eGFR 33 mL/min/1.73 m2, Ca 2.19 mmol/L, PO4 1.3 mmol/L, ALP 70 IU/L, iPTH < 0.1 pmol/L). Our case report highlights the therapeutic potential of pamidronate in addition to cinacalcet in the management of PT-HPT-associated nephrocalcinosis.

Timing of parathyroidectomy for tertiary hyperparathyroidism after kidney transplant

BACKGROUND

Parathyroidectomy has been shown to be superior to medical management in treating hypercalcemia and preserving renal allograft function in patients with tertiary hyperparathyroidism after kidney transplant. Despite this evidence, parathyroidectomy remains underused. We aimed to evaluate outcomes in patients with tertiary hyperparathyroidism after kidney transplant based on management strategy (cinacalcet or parathyroidectomy) and optimal timing of parathyroidectomy.

METHODS

Data from TriNetX Dataworks included adult kidney transplant patients diagnosed with tertiary hyperparathyroidism between 1998 and 2021. Patients who underwent parathyroidectomy were compared with those receiving cinacalcet. Subgroups based on parathyroidectomy timing after transplant were analyzed (within 6 months, 6 months to 1 year, and between 1 and 3 years). Descriptive statistics and relative risks were calculated using TriNetX Live.

RESULTS

Patients receiving cinacalcet (n = 162) had a 77% higher risk of persistent hypercalcemia and a 73% higher risk of elevated parathyroid hormone levels than those who underwent parathyroidectomy (n = 338) within 3-10 years after the index event (start of cinacalcet or surgery). Parathyroidectomy performed 1 year after transplant (n = 132) was associated with a 57% lower risk of kidney stone formation and patients were 2 times more likely to maintain normal glomerular filtration rate than parathyroidectomy performed 1-3 years after transplant (n = 57). Even earlier parathyroidectomy (within 6 months of kidney transplant, n = 55) showed a 62% lower risk of persistent hypercalcemia, hyperphosphatemia, and kidney stone formation than surgery between 6 months and 1 year after transplant (n = 77).

CONCLUSION

Parathyroidectomy is more effective than cinacalcet in managing tertiary hyperparathyroidism after kidney transplant. In addition, opting for early parathyroidectomy (within 6 months after transplant) could enhance long-term outcomes.

Approach to Late Noninfectious Post-Transplant Complications

The management of noninfectious complications in kidney transplant recipients includes a broad spectrum of conditions, including metabolic issues, cardiovascular diseases, and malignancies, each presenting unique challenges for nephrologists managing these patients. Unlike infectious complications, these noninfectious issues require nuanced, multidisciplinary approaches for prevention, diagnosis, and management, emphasizing the need for personalized care plans. Cardiovascular disease is particularly significant, standing as the primary cause of death post-transplantation, with recent data indicating an overtaking of cancer death rates over infections among kidney transplant recipients. The intricacies of managing these patients, influenced by the burden of kidney disease and immunosuppression, highlight the importance of a collaborative care model. Although nephrologists may not directly treat all these conditions, their understanding of the unique aspects of transplant recipients is crucial. They play a pivotal role in coordinating care with specialists such as cardiologists, endocrinologists, hematologists, and oncologists, ensuring comprehensive management that addresses these specific post-transplant complications. This review discusses the epidemiology, underlying mechanisms, clinical manifestations, and management strategies of various noninfectious complications post-kidney transplant, with a focus on cardiovascular, metabolic, oncologic, and hematologic complications.

Electrolyte and Acid-Base Abnormalities After Kidney Transplantation

Kidney transplantation is the optimal therapeutic approach for individuals with end-stage kidney disease. The Scientific Registry of Transplant Recipients has reported a continuous rise in the total number of kidney transplants performed in the United States, with 25,500 new kidney recipients in 2022 alone. Despite an improved glomerular filtration rate, the post-transplant period introduces a unique set of electrolyte abnormalities that differ from those encountered in chronic kidney disease. A variety of factors contribute to the high prevalence of hypomagnesemia, hyperkalemia, metabolic acidosis, hypercalcemia, and hypophosphatemia seen after kidney transplantation. These include the degree of allograft function, immunosuppressive medications and their diverse mechanisms of action, and metabolic changes after transplant. This article aims to provide a comprehensive review of the key aspects surrounding the most commonly encountered electrolyte and acid-base abnormalities in the post-transplant setting.

Etelcalcetide use During Maintenance Hemodialysis and Incidence of Parathyroidectomy After Kidney Transplantation

INTRODUCTION

Etelcalcetide is an i.v. calcimimetic agent, effectively reducing parathyroid hormone levels in patients on maintenance hemodialysis (HD). The clinical impact of discontinuing etelcalcetide at the time of kidney transplantation is unknown.

METHODS

We retrospectively reviewed all patients on HD meeting predefined criteria who received a kidney transplant at our institution between January 1, 2015, and December 12, 2022. The incidence of parathyroidectomy and the evolution of calcium, phosphate, and intact parathyroid hormone (iPTH) levels after transplantation was analyzed according to the type of calcimimetic treatment before transplantation (cinacalcet vs. etelcalcetide vs. none).

RESULTS

Overall, 372 patients (aged 53 years; interquartile range [IQR]: 42-62 years) were included. At the time of transplantation, 35, 75, and 262 patients were under etelcalcetide, cinacalcet, or no calcimimetic, respectively. After 1064 (IQR: 367-1658) days, the incidences of parathyroidectomy in the etelcalcetide, cinacalcet, no calcimimetic groups were 29%, 12%, and 1%, respectively (P < 0.001). Etelcalcetide was associated with an increased incidence of parathyroidectomy after adjustment for age, sex, and HD vintage (hazard ratio [HR]: 97.0, 95% confidence interval [CI]: 19.1-493.9, P < 0.001). The incidence of parathyroidectomy was related to etelcalcetide dosage (6/11 [54.6%] in patients with ≥ 10 mg vs. 4/24 [16.7%] in patients with < 10 mg, P = 0.02). Moreover, peak calcium levels were higher (P < 0.001) and parathyroidectomy was performed earlier (median 80 vs. 480 days, P < 0.001) in the etelcalcetide compared with the cinacalcet group. Long-term graft function, graft loss, and mortality were similar.

CONCLUSION

Etelcalcetide use during maintenance HD is associated with an increased incidence of early parathyroidectomy after transplantation compared to cinacalcet or no calcimimetic.

Bone health and fracture prevention after kidney transplantation

Changes in bone health and strength are common after kidney transplantation and can lead to an increased risk of fracture. This has implications for morbidity, mortality and renal allograft survival. This review will focus on the changes that occur in bone health and fracture risk after kidney transplantation and examine the evidence available to guide diagnostic and therapeutic decisions with the aim of fracture prevention.

Post-Transplant Bone Disease in Kidney Transplant Recipients: Diagnosis and Management

Kidney transplantation is the preferred gold standard modality of treatment for kidney failure. Bone disease after kidney transplantation is highly prevalent in patients living with a kidney transplant and is associated with high rates of hip fractures. Fractures are associated with increased healthcare costs, morbidity and mortality. Post-transplant bone disease (PTBD) includes renal osteodystrophy, osteoporosis, osteonecrosis and bone fractures. PTBD is complex as it encompasses pre-existing chronic kidney disease-mineral bone disease and compounding factors after transplantation, including the use of immunosuppression and the development of de novo bone disease. After transplantation, the persistence of secondary and tertiary hyperparathyroidism, renal osteodystrophy, relative vitamin D deficiency and high levels of fibroblast growth factor-23 contribute to post-transplant bone disease. Risk assessment includes identifying both general risk factors and kidney-specific risk factors. Diagnosis is complex as the gold standard bone biopsy with double-tetracycline labelling to diagnose the PTBD subtype is not always readily available. Therefore, alternative diagnostic tools may be used to aid its diagnosis. Both non-pharmacological and pharmacological therapy can be employed to treat PTBD. In this review, we will discuss pathophysiology, risk assessment, diagnosis and management strategies to manage PTBD after kidney transplantation.

Non-Traditional Non-Immunological Risk Factors for Kidney Allograft Loss-Opinion

Rates of late allograft loss have improved slowly in the last decades. Well described traditional risk factors that influence allograft survival include cardiovascular events, rejection, infections and post-transplant neoplasia. Here, we critically evaluate the influence of several non-immunological, non-traditional risk factors and describe their impact on allograft survival and cardiovascular health of kidney transplant recipients. We assessed the following risk factors: arterial stiffness, persistent arteriovenous access, mineral bone disease, immunosuppressive drugs residual levels variability, hypomagnesemia, glomerular pathological alterations not included in Banff criteria, persistent inflammation and metabolic acidosis.

Parathyroidectomy and Cinacalcet Use in Medicare-Insured Kidney Transplant Recipients

RATIONALE & OBJECTIVE

Posttransplant hyperparathyroidism is common, and treatment practices are poorly characterized. The goal of this study was to examine the incidence, associations, and outcomes of posttransplant parathyroidectomy and calcimimetic use in a cohort of Medicare-insured US kidney transplant recipients.

STUDY DESIGN

Retrospective observational cohort study.

SETTING & PARTICIPANTS

We used the US Renal Data System to extract demographic, clinical, and prescription data from Medicare Parts A, B, and D-insured patients who received their first kidney transplant in 2007-2013. We excluded patients with pretransplant parathyroidectomy.

PREDICTORS

Calendar year of transplantation and pretransplant patient characteristics.

OUTCOME

(1) Incidence of and secular trends in parathyroidectomy and cinacalcet use in the 3 years after transplant; (2) 90-day outcomes after posttransplant parathyroidectomy and cinacalcet initiation.

ANALYTICAL APPROACH

Temporal trends and pretransplant correlates of parathyroidectomy and cinacalcet use were assessed using proportional hazards models and multivariable Poisson regression, respectively.

RESULTS

The inclusion criteria were met by 30,127 patients, of whom 10,707 used cinacalcet before transplant, 551 underwent posttransplant parathyroidectomy, and 5,413 filled≥1 prescription for cinacalcet. The rate of posttransplant parathyroidectomy was stable over time. By contrast, cinacalcet use increased during the period studied. Long dialysis vintage and pretransplant cinacalcet use were strongly associated with posttransplant parathyroidectomy and cinacalcet use. Roughly 1 in 4 patients were hospitalized within 90 days of posttransplant parathyroidectomy, with hypocalcemia-related diagnoses being the most common complication. Parathyroidectomy (vs cinacalcet initiation) was not associated with an increase in acute kidney injury.

LIMITATIONS

We lacked access to laboratory data to help assess the severity of secondary/tertiary hyperparathyroidism. The cohort was limited to Medicare beneficiaries.

CONCLUSIONS

Almost one-fifth of our study cohort was treated with parathyroidectomy and/or cinacalcet. Further studies are needed to establish the optimal treatment for posttransplant hyperparathyroidism.

Persistent hyperparathyroidism in long-term kidney transplantation: time to consider a less aggressive approach

PURPOSE OF REVIEW

Persistent hyperparathyroidism affects 50% of long-term kidney transplants with preserved allograft function. Timing, options and the optimal target for treatment remain unclear. Clinical practice guidelines recommend the same therapeutic approach as patients with chronic kidney disease.

RECENT FINDINGS

Mild to moderate elevation of parathyroid hormone (PTH) levels in long-term kidney transplants may not be associated with bone loss and fracture. Recent findings on bone biopsy revealed the lack of association between hypercalcaemic hyperparathyroidism with pathology of high bone turnover. Elevated PTH levels may be required to maintain normal bone volume. Nevertheless, several large observational studies have revealed the association between hypercalcemia and the elevation of PTH levels with unfavourable allograft and patient outcomes. Both calcimimetics and parathyroidectomy are effective in lowering serum calcium and PTH. A recent meta-analysis suggested parathyroidectomy may be performed safely after kidney transplantation without deterioration of allograft function.

SUMMARY

Treatment of persistent hyperparathyroidism is warranted in kidney transplants with hypercalcemia and markedly elevated PTH levels. A less aggressive approach should be applied to those with mild to moderate elevation. Whether treatments improve outcomes remain to be elucidated.

Two-way Road of Kidney and Hypercalcemia: A Narrative Review

Calcium homeostasis is regulated by the dyad of parathyroid hormone and calcitriol, whereas kidney, intestine, and bone are the primary target sites. Elevation of serum calcium levels and hypercalcemia are likely markers of pathological conditions, particularly malignancy and hyperparathyroidism. Similarly, several dysfunctions within the body can direct hypercalcemia. Furthermore, chemicals and drugs can also drive this condition. Owing to the significant role of the kidney in calcium homeostasis, renal abnormalities lead to hypercalcemia and increased calcium levels can have pathological effects on the kidney. This review is designed to highlight some of the commonly known causes of hypercalcemia and their effects on the kidney.

Systematic Review of the Treatment of Persistent Hyperparathyroidism Following Kidney Transplantation

Chronic kidney disease-mineral and bone disorder is one of the complications associated with chronic kidney disease. About 10-50% of patients following kidney transplantation have persistent hyperparathyroidism. Hypercalcaemic hyperparathyroidism has a negative impact on the kidney transplant outcome; therefore, it requires treatment. The data regarding the treatment of persistent hyperparathyroidism provided in scientific publications are divergent and contradictory. Therefore, the aim of our systematic review was to evaluate the efficacy of persistent hyperparathyroidism treatment in patients following kidney transplantation. The Cochrane, PubMed, and Scopus databases were browsed independently by two authors. The search strategy included controlled vocabulary and keywords. The effectiveness of calcitriol, paricalcitol, cinacalcet, and parathyroidectomy was compared and analysed. The mean calcium and parathormone (PTH) concentrations per patient in the group of paricalcitol increased by 1.27% and decreased by 35.14% (n = 248); in the group of cinacalcet decreased by 12.09% and 32.16% (n = 368); and in the group of parathyroidectomy decreased by 19.06% and 86.49% (n = 15) at the end of the study compared to the baseline (n = 244, n = 342 and n = 15), respectively. Paricalcitol, cinacalcet, and parathyroidectomy decreased the intact PTH level. Cinacalcet and parathyroidectomy lowered calcium levels in renal transplant patients with hypercalcaemia. Conversely, paricalcitol increased the serum calcium concentration. Cinacalcet seems to be a good candidate in the treatment of post-transplant hyperparathyroidism.

The American Association of Endocrine Surgeons Guidelines for the Definitive Surgical Management of Secondary and Tertiary Renal Hyperparathyroidism

OBJECTIVE

To develop evidence-based recommendations for safe, effective, and appropriate treatment of secondary (SHPT) and tertiary (THPT) renal hyperparathyroidism.

BACKGROUND

Hyperparathyroidism is common among patients with chronic kidney disease, end-stage kidney disease, and kidney transplant. The surgical management of SHPT and THPT is nuanced and requires a multidisciplinary approach. There are currently no clinical practice guidelines that address the surgical treatment of SHPT and THPT.

METHODS

Medical literature was reviewed from January 1, 1985 to present January 1, 2021 by a panel of 10 experts in SHPT and THPT. Recommendations using the best available evidence was constructed. The American College of Physicians grading system was used to determine levels of evidence. Recommendations were discussed to consensus. The American Association of Endocrine Surgeons membership reviewed and commented on preliminary drafts of the content.

RESULTS

These clinical guidelines present the epidemiology and pathophysiology of SHPT and THPT and provide recommendations for work-up and management of SHPT and THPT for all involved clinicians. It outlines the preoperative, intraoperative, and postoperative management of SHPT and THPT, as well as related definitions, operative techniques, morbidity, and outcomes. Specific topics include Pathogenesis and Epidemiology, Initial Evaluation, Imaging, Preoperative and Perioperative Care, Surgical Planning and Parathyroidectomy, Adjuncts and Approaches, Outcomes, and Reoperation.

CONCLUSIONS

Evidence-based guidelines were created to assist clinicians in the optimal management of secondary and tertiary renal hyperparathyroidism.

Bone and Mineral Disorder in Renal Transplant Patients: Overview of Pathology, Clinical, and Therapeutic Aspects

Renal transplantation (RTx) allows us to obtain the resolution of the uremic status but is not frequently able to solve all the metabolic complications present during end-stage renal disease. Mineral and bone disorders (MBDs) are frequent since the early stages of chronic kidney disease (CKD) and strongly influence the morbidity and mortality of patients with CKD. Some mineral metabolism (MM) alterations can persist in patients with RTx (RTx-p), as well as in the presence of complete renal function recovery. In those patients, anomalies of calcium, phosphorus, parathormone, fibroblast growth factor 23, and vitamin D such as bone and vessels are frequent and related to both pre-RTx and post-RTx specific factors. Many treatments are present for the management of post-RTx MBD. Despite that, the guidelines that can give clear directives in MBD treatment of RTx-p are still missed. For the future, to obtain an ever-greater individualisation of therapy, an increase of the evidence, the specificity of international guidelines, and more uniform management of these anomalies worldwide should be expected. In this review, the major factors related to post-renal transplant MBD (post-RTx-MBD), the main mineral metabolism biochemical anomalies, and the principal treatment for post-RTx MBD will be reported.

Natural History of Bone Disease following Kidney Transplantation

BACKGROUND

Knowledge of the effect of kidney transplantation on bone is limited and fragmentary. The aim of this study was to characterize the evolution of bone disease in the first post-transplant year.

METHODS

We performed a prospective, observational cohort study in patients referred for kidney transplantation under a steroid-sparing immunosuppressive protocol. Bone phenotyping was done before, or at the time of, kidney transplantation, and repeated at 12 months post-transplant. The phenotyping included bone histomorphometry, bone densitometry by dual-energy x-ray absorptiometry, and biochemical parameters of bone and mineral metabolism.

RESULTS

Paired data were obtained for 97 patients (median age 55 years; 72% male; 21% of patients had diabetes). Bone turnover remained normal or improved in the majority of patients (65%). Bone histomorphometry revealed decreases in bone resorption (eroded perimeter, mean 4.6% pre- to 2.3% post-transplant; P<0.001) and disordered bone formation (fibrosis, 27% pre- versus 2% post-transplant; P<0.001). Whereas bone mineralization was normal in all but one patient pretransplant, delayed mineralization was seen in 15% of patients at 1 year post-transplant. Hypophosphatemia was associated with deterioration in histomorphometric parameters of bone mineralization. Changes in bone mineral density were highly variable, ranging from -18% to +17% per year. Cumulative steroid dose was related to bone loss at the hip, whereas resolution of hyperparathyroidism was related to bone gain at both spine and hip.

CONCLUSIONS

Changes in bone turnover, mineralization, and volume post-transplant are related both to steroid exposure and ongoing disturbances of mineral metabolism. Optimal control of mineral metabolism may be key to improving bone quality in kidney transplant recipients.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Evolution of Bone Histomorphometry and Vascular Calcification Before and After Renal Transplantation, NCT01886950.

Bone and Mineral Disease in Kidney Transplant Recipients

After kidney transplantation, mineral and bone disorders are associated with higher risk of fractures and consequent morbidity and mortality. Disorders of calcium and phosphorus, vitamin D deficiency, and hyperparathyroidism are also common. The epidemiology of bone disease has evolved over the past several decades due to changes in immunosuppressive regimens, mainly glucocorticoid minimization or avoidance. The assessment of bone disease in kidney transplant recipients relies on risk factor recognition and bone mineral density assessment. Several drugs have been trialed for the treatment of post-transplant mineral and bone disorders. This review will focus on the epidemiology, effect, and treatment of metabolic and skeletal derangements in the transplant recipient.

Tertiary and Postrenal Transplantation Hyperparathyroidism

Patients who have undergone kidney transplantation (KTx) (KTxps) are a distinctive population characterized by the persistence of some metabolic anomalies present during end-stage renal disease. Mineral metabolism (MM) parameters are frequently altered after KTx. These alterations involve calcium, phosphorus, vitamin D, and parathormone (PTH) disarrangements. At present, there is little consensus about the correct monitoring and management of PTH disorders in KTxps. This article presents the prevalence and epidemiologic and clinical impact of post-KTx hyper-PTH. The principal biochemical and instrumental investigations and the therapeutic options for these conditions are also reported.

Association of time-updated plasma calcium and phosphate with graft and patient outcomes after kidney transplantation

Disturbances in calcium-phosphate homeostasis are common after kidney transplantation. We aimed to assess the relationship between deregulations in plasma calcium and phosphate over time and mortality and death-censored graft failure (DCGF). In this prospective cohort study, we included kidney transplant recipients with ≥2 plasma calcium and phosphate measurements. Data were analyzed using time-updated Cox regression analyses adjusted for potential confounders including time-updated kidney function. We included 2769 patients (mean age 47 ± 14 years, 42.3% female) with 138 496 plasma calcium and phosphate levels (median [IQR] 43 [31-61] measurements per patient). During follow-up of 16.3 [8.7-25.2] years, 17.2% developed DCGF and 7.9% died. Posttransplant hypercalcemia was associated with an increased risk of mortality (1.63 [1.31-2.00], p < 0.0001), but not with DCGF. Hyperphosphatemia was associated with both DCGF (2.59 [2.05-3.27], p < .0001) and mortality (3.14 [2.58-3.82], p <  .0001). Only the association between hypercalcemia and mortality remained significant in sensitivity analyses censored by a simultaneous eGFR <45 mL/min/1.73 m2 . Hypocalcemia and hypophosphatemia were not consistently associated with either outcome. Posttransplant hypercalcemia, even in the presence of preserved kidney function, was associated with an increased mortality risk. Associations of hyperphosphatemia with DCGF and mortality may be driven by eGFR.

Parathyroidectomy or cinacalcet: Do we still not know the best option for graft function in kidney-transplanted patients? A meta-analysis

BACKGROUND

Tertiary hyperparathyroidism occurs in 25% to 50% of kidney-transplanted patients. Indication of parathyroidectomy is now discussed, since the calcimimetic agent, cinacalcet, is an alternate option. The effects of either of these treatments on graft function remain controversial, studied only in small cohorts showing either decrease or absence of modification. We performed a meta-analysis to evaluate the evolution of graft function after surgical or medical treatment.

METHODS

Studies assessing graft function in tertiary hyperparathyroidism after parathyroidectomy or cinacalcet introduction were enrolled into quantitative analysis using Pubmed, Embase, and Cochrane databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis reporting guidelines. Among 68 screened studies, 18 had no missing data and were included for statistical analyses. We performed random effect meta-analysis to determine changes in serum creatinine and estimated glomerular filtration rate.

RESULTS

Seven studies assessing the evolution of graft function 6 and/or 12 months after parathyroidectomy and 13 after administration of cinacalcet were included. Meta-analysis found no significant variations after parathyroidectomy in serum creatinine (6 studies, 314 patients) and estimated glomerular filtration rate (2 studies, 105 patients). No significant variation was found after administration of cinacalcet in serum creatinine (10 studies, 404 patients) and estimated glomerular filtration rate (6 studies, 149 patients). A significant heterogeneity between the studies (P < .01, Cochran's Q) was found.

CONCLUSION

Meta-analysis shows that parathyroidectomy and cinacalcet do not significantly impair graft function in patients with tertiary hyperparathyroidism. However, the significant heterogeneity between selected studies, partially explained by the lack of consensual definition of tertiary hyperparathyroidism, limits the conclusions of all previously published series.

Mineral Bone Disorders in Kidney Transplantation

Bone disease after kidney transplantation is associated with an increased risk of fractures, morbidity, and mortality. Its pathophysiology is complex, involving multiple contributors including pretransplant bone disease, immunosuppressive medications, and changes in the parathyroid-bone-kidney axis. Risk scores, bone turnover markers, and noninvasive imaging modalities are only able to partially predict the fracture risk in kidney transplant recipients. The optimal management of bone disease after kidney transplantation has not yet been established, with only a limited number of randomized clinical trials evaluating the efficacy of treatment regimens in kidney transplant recipients. This review focuses on the pathophysiology, evaluation, prevention, and treatment of post-kidney transplant mineral and bone disease as guided by recent evidence.

Bone Mineral Density and Aortic Calcification: Evidence for a Bone-vascular Axis After Kidney Transplantation

BACKGROUND

Chronic kidney disease mineral and bone disorders (CKD-MBD) and vascular calcification are often seen in kidney transplantation recipients (KTR). This study focused on the bone-vascular axis hypothesis, the pathophysiological mechanisms driving both bone loss and vascular calcification, supported by an association between lower bone mineral density (BMD) and higher risk of vascular calcification.

METHODS

KTR referred for a dual-energy X-ray absorptiometry procedure within 6 mo after transplantation were included in a cross-sectional study (2004-2014). Areal BMD was measured at the proximal femur, and abdominal aortic calcification (AAC) was quantified (8-points score) from lateral single-energy images of the lumbar spine. Patients were divided into 3 AAC categories (negative-AAC: AAC 0; low-AAC: AAC 1-3; and high-AAC: AAC 4-8). Multivariable-adjusted multinomial logistic regression models were performed to study the association between BMD and AAC.

RESULTS

We included 678 KTR (51 ± 13 y old, 58% males), 366 (54%) had BMD disorders, and 266 (39%) had detectable calcification. High-AAC was observed in 9%, 11%, and 25% of KTR with normal BMD, osteopenia, and osteoporosis, respectively (P < 0.001). Higher BMD (T-score, continuous) was associated with a lower risk of high-AAC (odds ratio 0.61, 95% confidence interval 0.42-0.88; P = 0.008), independent of age, sex, body mass index, estimated glomerular filtration rate, and immunosuppressive therapy. KTR with normal BMD were less likely to have high-AAC (odds ratio 0.24, 95% confidence interval 0.08-0.72; P = 0.01).

CONCLUSIONS

BMD disorders are highly prevalent in KTR. The independent inverse association between BMD and AAC may provide evidence to point toward the existence, while highlighting the clinical and epidemiological relevance, of a bone-vascular axis after kidney transplantation.

The use of cinacalcet after pediatric renal transplantation: an international CERTAIN Registry analysis

BACKGROUND

Secondary hyperparathyroidism (SHPT) may persist after renal transplantation (RTx), inducing hypophosphatemia and hypercalcemia that precludes the use of vitamin D analogs. The calcimimetic cinacalcet improved plasma calcium and parathyroid hormone (PTH) levels in randomized controlled trials in adults after RTx, but pediatric data are scarce.

METHODS

In this retrospective study, we analyzed 20 pediatric patients from the Cooperative European Paediatric Renal TransplAnt Initiative (CERTAIN) Registry who received cinacalcet after RTx. The results are presented as median and interquartile range (25th-75th percentile).

RESULTS

At 13.7 (11.0-16.5) years of age, 20 pediatric patients received a renal allograft. Cinacalcet was introduced at 0.4 (0.3-2.7) years post-transplant at an estimated glomerular filtration rate (eGFR) of 50 (34-66) mL/min/1.73 m², plasma calcium of 2.58 (2.39-2.71) mmol/L, age-standardized (z score) phosphate of - 1.7 (- 2.7-- 0.4), and PTH of 136 (95-236) ng/L. The starting dose of cinacalcet was 0.5 (0.3-0.8) mg/kg per day, with a maximum dose of 1.1 (0.5-1.3) mg/kg per day. With a follow-up of 3.0 (1.5-3.6) years on cinacalcet therapy, eGFR remained stable; PTH levels decreased to 66 (56-124) ng/L at the last follow-up (p = 0.015). One patient displayed hypocalcemia (1.8 mmol/L). Cinacalcet was withdrawn in three patients (hypocalcemia, parathyroidectomy, incompliance). Nephrocalcinosis of the graft was not reported.

CONCLUSIONS

This pilot study suggests that cinacalcet as off-label therapy for SHPT after pediatric RTx is efficacious in controlling post-transplant SHPT with acceptable tolerability. Continuing cinacalcet even with normal PTH can lead to dangerous life-threatening hypocalcemia. Therefore, at each subsequent visit, the need to continue cinacalcet must be assessed.

Long-term results of a randomized study comparing parathyroidectomy with cinacalcet for treating tertiary hyperparathyroidism

Tertiary hyperparathyroidism is a common cause of hypercalcemia after kidney transplantation (KT) and has been associated with renal dysfunction, bone mineral density loss, and increased risk of fracture and cardiovascular events. In a previous 12-month clinical trial, we demonstrated that subtotal parathyroidectomy was more effective than cinacalcet for controlling hypercalcemia. In the current study, we retrospectively evaluate whether this effect is maintained after 5 years of follow-up. In total, 24 patients had data available at 5 years, 13 in the cinacalcet group and 11 in the parathyroidectomy group. At 5 years, 7 of 11 patients (64%) in the parathyroidectomy group and 6 of 13 patients (46%) in the cinacalcet group (P = .44) showed normocalcemia. However, recurrence of hypercalcemia was only observed in the cinacalcet group (P = .016). Subtotal parathyroidectomy retained a greater reduction in intact parathyroid hormone (iPTH) compared with cinacalcet group. No differences were observed in kidney function and incidence of fragility fractures between both groups. Cinacalcet was discontinued in 5 out of 13 patients. In conclusion, in kidney transplant patients with tertiary hyperparathyroidism recurrence of hypercalcemia after 5-year follow-up is more frequent in cinacalcet than after subtotal parathyroidectomy.

Bone biomarkers in de novo renal transplant recipients

Successful kidney transplantation (partly) corrects the physiologic and metabolic abnormalities driving chronic kidney disease - mineral and bone disorders. At the same time, renal transplant recipients are exposed to immunosuppressive agents that may affect bone metabolism. Bone biomarkers have been suggested as surrogates of or adjuncts to bone biopsy and imaging techniques to assess bone health and to classify risk of bone loss and fractures. Bone biomarkers may be classified as circulating factors that affect bone metabolism (commonly referred to as bone metabolism markers) or that reflect bone cell number and/or activity (commonly referred to as bone turnover markers). A growing body of evidence shows that successful renal transplantation has a major impact on both bone metabolism and bone turnover. Analytical issues, including the cross-reactivity with fragments, complicate the interpretation of bone biomarkers, especially in the setting of a rapid changing kidney function, as is the case after successful renal transplantation. Overall, bone turnover seems to decline following renal transplantation, but inter-individual variability is substantial. Preliminary evidence indicates that bone biomarkers may be useful in guiding mineral and bone therapy in renal transplant recipients.

Interventions for preventing bone disease in kidney transplant recipients

BACKGROUND

People who have chronic kidney disease (CKD) have important changes to bone structure, strength, and metabolism. Children experience bone deformity, pain, and delayed or impaired growth. Adults experience limb and vertebral fractures, avascular necrosis, and pain. The fracture risk after kidney transplantation is four times that of the general population and is related to Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD) occurring with end-stage kidney failure, steroid-induced bone loss, and persistent hyperparathyroidism after transplantation. Fractures may reduce quality of life and lead to being unable to work or contribute to community roles and responsibilities. Earlier versions of this review have found low certainty evidence for effects of treatment. This is an update of a review first published in 2005 and updated in 2007.

OBJECTIVES

This review update evaluates the benefits and harms of interventions for preventing bone disease following kidney transplantation.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 16 May 2019 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

RCTs and quasi-RCTs evaluating treatments for bone disease among kidney transplant recipients of any age were eligible.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial risks of bias and extracted data. Statistical analyses were performed using random effects meta-analysis. The risk estimates were expressed as a risk ratio (RR) for dichotomous variables and mean difference (MD) for continuous outcomes together with the corresponding 95% confidence interval (CI). The primary efficacy outcome was bone fracture. The primary safety outcome was acute graft rejection. Secondary outcomes included death (all cause and cardiovascular), myocardial infarction, stroke, musculoskeletal disorders (e.g. skeletal deformity, bone pain), graft loss, nausea, hyper- or hypocalcaemia, kidney function, serum parathyroid hormone (PTH), and bone mineral density (BMD).

MAIN RESULTS

In this 2019 update, 65 studies (involving 3598 participants) were eligible; 45 studies contributed data to our meta-analyses (2698 participants). Treatments included bisphosphonates, vitamin D compounds, teriparatide, denosumab, cinacalcet, parathyroidectomy, and calcitonin. Median duration of follow-up was 12 months. Forty-three studies evaluated bone density or bone-related biomarkers, with more recent studies evaluating proteinuria and hyperparathyroidism. Bisphosphonate therapy was usually commenced in the perioperative transplantation period (within 3 weeks) and regardless of BMD. Risks of bias were generally high or unclear leading to lower certainty in the results. A single study reported outcomes among 60 children and adolescents. Studies were not designed to measure treatment effects on fracture, death or cardiovascular outcomes, or graft loss.Compared to placebo, bisphosphonate therapy administered over 12 months in transplant recipients may prevent fracture (RR 0.62, 95% CI 0.38 to 1.01; low certainty evidence) although the 95% CI included the possibility that bisphosphonate therapy might make little or no difference. Fracture events were principally vertebral fractures identified during routine radiographic surveillance. It was uncertain whether any other drug class decreased fracture (low or very low certainty evidence). It was uncertain whether interventions for bone disease in kidney transplantation reduce all-cause or cardiovascular death, myocardial infarction or stroke, or graft loss in very low certainty evidence. Bisphosphonate therapy may decrease acute graft rejection (RR 0.70, 95% CI 0.55 to 0.89; low certainty evidence), while it is uncertain whether any other treatment impacts graft rejection (very low certainty evidence). Bisphosphonate therapy may reduce bone pain (RR 0.20, 95% CI 0.04 to 0.93; very low certainty evidence), while it was very uncertain whether bisphosphonates prevent spinal deformity or avascular bone necrosis (very low certainty evidence). Bisphosphonates may increase to risk of hypocalcaemia (RR 5.59, 95% CI 1.00 to 31.06; low certainty evidence). It was uncertain whether vitamin D compounds had any effect on skeletal, cardiovascular, death, or transplant function outcomes (very low certainty or absence of evidence). Evidence for the benefits and harms of all other treatments was of very low certainty. Evidence for children and young adolescents was sparse.

AUTHORS' CONCLUSIONS

Bisphosphonate therapy may reduce fracture and bone pain after kidney transplantation, however low certainty in the evidence indicates it is possible that treatment may make little or no difference. It is uncertain whether bisphosphonate therapy or other bone treatments prevent other skeletal complications after kidney transplantation, including spinal deformity or avascular bone necrosis. The effects of bone treatment for children and adolescents after kidney transplantation are very uncertain.

Effect of Cinacalcet in Kidney Transplant Patients With Hyperparathyroidism

OBJECTIVE

In dialysis patients, cinacalcet could be an effective alternative to parathyroidectomy for treating hyperparathyroidism. In the present study, we aimed to determine the characteristics of subjects with persistent hyperparathyroidism who require parathyroidectomy despite the use of cinacalcet.

METHODS

Nine kidney transplant patients (7 men, 2 women; mean age 53.2 [SD, 8.9] years) who had tertiary hyperparathyroidism were reviewed in a single center. Pre- and postcinacalcet levels of calcium, phosphorous, intact parathyroid hormone (iPTH), and renal function were analyzed to evaluate the effect of cinacalcet treatment in these patients. The baseline parameters before cinacalcet treatment were compared in patients who did and did not undergo parathyroidectomy.

RESULTS

Cinacalcet reduced serum calcium levels in all patients (11.48 [SD, 0.73] mg/dL to 10.20 [0.70] mg/dL; P = .008). Serum phosphorous levels significantly increased from 2.28 (SD, 0.77) mg/dL to 3.02 (SD, 0.65) mg/dL (P = .03). The iPTH levels in 7 patients decreased, while the mean level remained unchanged in total subjects. The iPTH levels increased even with cinacalcet treatment in 2 patients. In 3 patients, serum calcium levels abruptly increased after cinacalcet withdrawal. Five patients who showed persistent hypercalcemia due to hyperparathyroidism underwent parathyroidectomy. These 5 patients had significantly different characteristics compared with 4 patients who did not undergo parathyroidectomy: hypercalcemia (11.92 [SD, 0.68] mg/dL vs 10.93 [SD, 0.26] mg/dL; P = .02), hypophosphatemia (1.74 [SD, 0.36] mg/dL vs 2.95 [SD, 0.58] mg/dL; P = .03), and hyperparathyroidism (252.2 [SD, 131.4] pg/dL vs 101.5 [SD, 18.4] pg/dL; P = .02).

CONCLUSION

Cinacalcet reduced hypercalcemia due to hyperparathyroidism in the transplant patients. However, patients who had pre-existing higher iPTH, hypercalcemia, and hypophosphatemia needed parathyroidectomy. Therefore, cinacalcet could be considered an alternative to parathyroidectomy in selected patients.

Management of Post-transplant Hyperparathyroidism and Bone Disease

Significant advances in immunosuppressive therapies have been made in renal transplantation, leading to increased allograft and patient survival. Despite improvement in overall patient survival, patients continue to require management of persistent post-transplant hyperparathyroidism. Medications that treat persistent hyperparathyroidism include vitamin D, vitamin D analogues, and calcimimetics. Medication side effects such as hypocalcemia or hypercalcemia, and adynamic bone disease, may lead to a decrease in the drugs. When medical management fails to control persistent post-transplant hyperparathyroidism, treatment is a parathyroidectomy. Surgical techniques are not uniform between centers and surgeons. Undergoing the surgery may include a subtotal technique or a technique including total parathyroid gland resection with partial heterotopic gland reimplantation. In addition, there are possible post-surgical complications. The ideal treatment for persistent post-transplant hyperparathyroidism is the treatment and prevention of the condition while patients are being managed for their late-stage chronic kidney disease and end-stage renal disease.

An open-label, single-dose study to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of cinacalcet in pediatric subjects aged 28 days to < 6 years with chronic kidney disease receiving dialysis

BACKGROUND

Calcimimetics, shown to control biochemical parameters of secondary hyperparathyroidism (SHPT), have well-established safety and pharmacokinetic profiles in adult end-stage renal disease subjects treated with dialysis; however, such studies are limited in pediatric subjects.

METHODS

In this study, the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of cinacalcet were evaluated in children with chronic kidney disease (CKD) and SHPT receiving dialysis. Twelve subjects received a single dose of cinacalcet (0.25 mg/kg) orally or by nasogastric or gastric tube. Subjects were randomized to one of two parathyroid hormone (PTH) and serum calcium sampling sequences: [(1) 2, 8, 48 h; or (2) 2, 12, 48 h] and assessed for 72 h after dosing.

RESULTS

Median plasma cinacalcet t_max was 1 h (range 0.5-4.0 h); mean (SD) C_max and AUC_last were 2.83 (1.98) ng/mL and 11.8 (8.74) h*ng/mL, respectively; mean (SD) half-life (t_1/2) was 3.70 (2.57) h. Dose adjustments, based upon body weight (mg/kg), minimized the effects of age, body weight, body surface area, and body mass index on cinacalcet PK. Reductions in serum PTH levels from baseline were observed at 2 to 8 h post-dose (median 10.8 and 29.6%, respectively), returned towards baseline by 12-72 h and were inversely related to changes in the plasma cinacalcet PK profile. Single-dose cinacalcet was well-tolerated with no unexpected safety findings and a PK/PD, safety profile similar to adults.

CONCLUSIONS

In conclusion, a single 0.25 mg/kg dose of cinacalcet was evaluated to be a safe starting dose in these children aged < 6 years.

Mineral and Bone Disease in Kidney Transplant Recipients

PURPOSE OF REVIEW

Despite metabolic improvements following kidney transplantation, transplant recipients still often suffer from complex mineral and bone disease after transplantation.

RECENT FINDINGS

The pathophysiology of post-transplant disease is unique, secondary to underlying pre-transplant mineral and bone disease, immunosuppression, and changing kidney function. Changes in modern immunosuppression regimens continue to alter the clinical picture. Modern management includes reducing cumulative steroid exposure and correcting the biochemical abnormalities in mineral metabolism. While bone mineral density screening appears to help predict fracture risk and anti-osteoporotic therapy appears to have a positive effect on bone mineral density, more data regarding specific treatment is necessary. Patients with mineral and bone disease after kidney transplantation require special care in order to properly manage and mitigate their mineral and bone disease. Recent changes in clinical management of transplant patients may also be changing the implications on patients' mineral and bone disease.

Outcomes of bisphosphonate and its supplements for bone loss in kidney transplant recipients: a systematic review and network meta-analysis

BACKGROUND

Mineral bone disease constitutes a common complication of post-kidney transplantation, leading to great disability. As there is no consensus on the optimal treatment for post-kidney transplant recipients (KTRs), we aimed to evaluate the efficacy and safety of bisphosphonate and its combined therapies.

METHODS

We incorporated relevant trials to perform a network meta-analysis from direct and indirect comparisons. We searched PubMed, Embase and the CENTRAL and the reference lists of relevant articles up to August 1, 2017, for randomized controlled trials. The primary outcome was bone mineral density (BMD) change at the femoral neck and the lumbar spine.

RESULTS

From a total of 864 citations, 18 randomized controlled trials with a total of 1200 participants were included. Five different regimens were considered. Bisphosphonate plus calcium revealed a significant gain in percent BMD change than calcium alone at the femoral neck (mean difference (MD), 5.83; 95% credible interval (CrI), 1.61 to 9.27). No significant difference was detected when restricting to absolute terms. At the lumbar spine, bisphosphonate and calcium with or without vitamin D analogs outperformed calcium solely (MD, 0.07; 95% CrI, 0.00 to 0.13; MD, 0.06; 95% CrI, 0.02 to 0.09). Compared to calcium with vitamin D analogs, adding bisphosphonate was associated with marked improvement (MD, 0.03; 95% CrI, 0.00 to 0.05). Considering percent terms, combination of bisphosphonate with calcium and vitamin D analogs showed greater beneficial effects than calcium alone or with either vitamin D analogs or calcitonin (MD, 10.51; 95% CrI, 5.92 to 15.34; MD, 5.48; 95% CrI, 2.57 to 8.42; MD, 6.39; 95% CrI, 0.55 to 12.89). Both bisphosphonate and vitamin D analogs combined with calcium displayed a notable improvement compared to calcium alone (MD, 7.24; 95% CrI, 3.73 to 10.69; MD, 5.02; 95% CrI, 1.20 to 8.84).

CONCLUSIONS

Our study suggested that additional use of bisphosphonate was well-tolerated and more favorable in KTRs to improve BMD.

Electrolyte and Acid-Base Disorders in the Renal Transplant Recipient

Kidney transplantation is the current treatment of choice for patients with end-stage renal disease. Innovations in transplantation and immunosuppression regimens have greatly improved the renal allograft survival. Based on recently published data from the Scientific Registry of Transplant recipients, prevalence of kidney transplants is steadily rising in the United States. Over 210,000 kidney transplant recipients were alive with a functioning graft in mid-2016, which is nearly twice as many as in 2005. While successful renal transplantation corrects most of the electrolyte and mineral abnormalities seen in advanced renal failure, the abnormalities seen in the post-transplant period are surprisingly different from those seen in chronic kidney disease. Multiple factors contribute to the high prevalence of these abnormalities that include level of allograft function, use of immunosuppressive medications and metabolic changes in the post-transplant period. Electrolyte disturbances are common in patients after renal transplantation, and several studies have tried to determine the clinical significance of these disturbances. In this manuscript we review the key aspects of the most commonly found post-transplant electrolyte abnormalities. We focus on their epidemiology, pathophysiology, clinical manifestations, and available treatment approaches.

Mineral and Bone Disorders After Kidney Transplantation

The risk of mineral and bone disorders among patients with chronic kidney disease is substantially elevated, owing largely to alterations in calcium, phosphorus, vitamin D, parathyroid hormone, and fibroblast growth factor 23. The interwoven relationship among these minerals and hormones results in maladaptive responses that are differentially affected by the process of kidney transplantation. Interpretation of conventional labs, imaging, and other fracture risk assessment tools are not standardized in the post-transplant setting. Post-transplant bone disease is not uniformly improved and considerable variation exists in monitoring and treatment practices. A spectrum of abnormalities such as hypophosphatemia, hypercalcemia, hyperparathyroidism, osteomalacia, osteopenia, and osteoporosis are commonly encountered in the post-transplant period. Thus, reducing fracture risk and other bone-related complications requires recognition of these abnormalities along with the risk incurred by concomitant immunosuppression use. As kidney transplant recipients continue to age, the drivers of bone disease vary throughout the post-transplant period among persistent hyperparathyroidism, de novo hyperparathyroidism, and osteoporosis. The use of anti-resorptive therapies require understanding of different options and the clinical scenarios that warrant their use. With limited studies underscoring clinical events such as fractures, expert understanding of MBD physiology, and surrogate marker interpretation is needed to determine ideal and individualized therapy.

Management of mineral and bone disorders in renal transplant recipients

The management of post-transplantation bone disease is a complex problem that remains under-appreciated in clinical practice. In these patients, pre-existing metabolic bone disorder is further impacted by the use of immunosuppressive medications (glucocorticoids and calcineurin-inhibitors), variable post-transplantation renal allograft function and post-transplantation diabetes mellitus. The treatment of post-transplantation bone loss should begin pre-transplantation. All patients active on transplant waiting lists should be screened for bone disease. Patients should also be encouraged to take preventative measures against osteoporosis such as regular weight-bearing exercise, smoking cessation and reducing alcohol consumption. Biochemical abnormalities of disordered mineral metabolism should be corrected prior to transplantation wherever possible, and because these abnormalities commonly persist, post transplant hypophosphatemia, persistent hyperparathyroidism and low vitamin D levels should be regularly monitored and treated. Bone loss is greatest in the first 6-12 months post-transplantation, during which period any intervention is likely to be of greatest benefit. There is strong evidence that bisphosphonates prevent post-transplantation bone loss; however, data are lacking that this clearly extends to a reduction in fracture incidence. Denosumab is a potential alternative to vitamin D receptor agonists and bisphosphonates in reducing post-transplantation bone loss; however, further studies are needed to demonstrate its safety in patients with a significantly reduced estimated glomerular filtration rate. Clinical judgement remains the cornerstone of this complex clinical problem, providing a strong rationale for the formation of combined endocrinology and nephrology clinics to treat patients with Chronic Kidney Disease-Mineral and Bone Disorder, before and after transplantation.

Cinacalcet versus Placebo for secondary hyperparathyroidism in chronic kidney disease patients: a meta-analysis of randomized controlled trials and trial sequential analysis

To assess the efficacy and safety of cinacalcet on secondary hyperparathyroidism in patients with chronic kidney disease, Pubmed, Embase, and the Cochrane Central Register of Controlled Trials were searched until March 2016. Trial sequential analysis (TSA) was conducted to control the risks of type I and II errors and calculate required information size (RIS). A total of 25 articles with 8481 participants were included. Compared with controls, cinacalcet administration did not reduce all-cause mortality (RR = 0.97, 95% CI = 0.89–1.05, P = 0.41, TSA-adjusted 95% CI = 0.86–1.08, RIS = 5260, n = 8386) or cardiovascular mortality (RR = 0.95, 95% CI = 0.83–1.07, P = 0.39, TSA-adjusted 95% CI = 0.70–1.26, RIS = 3780 n = 5418), but it reduced the incidence of parathyroidectomy (RR = 0.48, 95% CI = 0.40–0.50, P < 0.001, TSA-adjusted 95% CI = 0.39–0.60, RIS = 5787 n = 5488). Cinacalcet increased the risk of hypocalcemia (RR = 8.48, 95% CI = 6.37–11.29, P < 0.001, TSA-adjusted 95% CI = 5.25–13.70, RIS = 6522, n = 7785), nausea (RR = 2.12, 95% CI = 1.62–2.77, P < 0.001, TSA-adjusted 95% CI = 1.45–3.04, RIS = 4684, n = 7512), vomiting (RR = 2.00, 95% CI = 1.79–2.24, P < 0.001, TSA-adjusted 95% CI = 1.77–2.26, RIS = 1374, n = 7331) and diarrhea (RR = 1.17, 95% CI = 1.05–1.32, P = 0.006, TSA-adjusted 95% CI = 1.02–1.36, RIS = 8388, n = 6116). Cinacalcet did not significantly reduce the incidence of fractures (RR = 0.58, 95% CI = 0.21–1.59, P = 0.29, TSA-adjusted 95% CI = 0.01–35.11, RIS = 76376, n = 4053). Cinacalcet reduced the incidence of parathyroidectomy, however, it did not reduce all-cause and cardiovascular mortality, and increased the risk of adverse events including hypocalcemia and gastrointestinal disorders.

Long-Term Use of Cinacalcet in Kidney Transplant Recipients With Hypercalcemic Secondary Hyperparathyroidism: A Single-Center Prospective Study

OBJECTIVES

Persistent secondary hyperparathyroidism is common after successful kidney transplant, with concomitant hypercalcemia and hypophosphatemia potentially leading to reduced graft survival and increased cardiovascular risk. Cinacalcet, a calcimimetic agent that activates the calcium-sensing receptors in parathyroid glands, is a therapeutic option. In this study, we assessed the long-term treatment effects of cinacalcet for a period of up to 5 years in a cohort of kidney transplant recipients.

MATERIALS AND METHODS

Forty-seven patients with secondary hyperparathyroidism (intact parathyroid hormone level > 70 pg/mL or 7.43 pmol/L) and hypercalcemia (corrected calcium > 10.4 mg/dL or 2.6 mmol/L) were considered eligible for treatment with cinacalcet and were included in the analysis. Data were recorded at initiation of treatment and every 6 months up to a maximum follow-up of 60 months. A control group of patients treated with placebo, conventional treatment, or surgical treatment was not available for this study.

RESULTS

Mean follow-up time was 45 ± 16 months. Treatment with cinacalcet was initiated at a median of 25 months after renal transplant. Serum calcium decreased by 0.21 mmol/L (2.69 vs 2.48 mmol/L; 95% confidence interval, 0.08-0.345; P < .001) during the first 6 months, and this reduction was sustained during follow-up. Intact parathyroid hormone level decreased by 7.68 pmol/L (32.96 ± 36.4 vs 25.28 ± 19.5 pmol/L; 95% confidence interval, -6.42 to 21.75; P = not significant) at 6 months, whereas at the end of follow-up intact parathyroid hormone level decreased further by 20.07 pmol/L (32.96 ± 36.4 vs 12.89 ± 5.73 pmol/L; 95% confidence interval, 2.02-38.1; P < .01). Mean starting dose of cinacalcet was 33.5 ± 10 mg/day. According to the therapeutic response, cinacalcet dose increased steadily and reached 51.1 ± 33 mg/day at the end of the observation period. Mean serum phosphorus increased significantly, whereas estimated glomerular filtration rate remained virtually stable throughout follow-up. Adverse reactions were observed in 4 patients, comprising mild gastro-intestinal complaints.

CONCLUSIONS

Long-term treatment with cinacalcet in kidney transplant recipients with secondary hyperparathyroidism is effective in controlling hypercalcemia and correcting hypophosphatemia, without affecting graft function while being well-tolerated.

Systematic review of surgical and medical treatment for tertiary hyperparathyroidism

BACKGROUND

A significant proportion of patients with chronic kidney disease and secondary hyperparathyroidism (HPT) remain hyperparathyroid after kidney transplantation, a state known as tertiary HPT. Without treatment, tertiary HPT can lead to diminished kidney allograft and patient survival. Parathyroidectomy was commonly performed to treat tertiary HPT until the introduction of the calcimimetic drug, cinacalcet. It is not known whether surgery or medical treatment is superior for tertiary HPT.

METHODS

A systematic review was performed and medical literature databases were searched for studies on the treatment of tertiary HPT that were published after the approval of cinacalcet.

RESULTS

A total of 1669 articles were identified, of which 47 were included in the review. Following subtotal and total parathyroidectomy, initial cure rates were 98·7 and 100 per cent respectively, but in 7·6 and 4 per cent of patients tertiary HPT recurred. After treatment with cinacalcet, 80·8 per cent of the patients achieved normocalcaemia. Owing to side-effects, 6·4 per cent of patients discontinued cinacalcet treatment. The literature regarding graft function and survival is limited; however, renal graft survival after surgical treatment appears comparable to that obtained with cinacalcet therapy.

CONCLUSION

Side-effects and complications of both treatment modalities were mild and occurred in a minority of patients. Surgical treatment for tertiary HPT has higher cure rates than medical therapy.

Combination Therapy of Denosumab and Calcitriol for a Renal Transplant Recipient with Severe Bone Loss due to Therapy-Resistant Hyperparathyroidism

Denosumab (DMAb), a complete human type monoclonal antibody directed against the receptor activator of nuclear factor-κB ligand, has gained attention as a novel treatment for osteoporosis. However, its efficacy in patients with chronic kidney disease (CKD) remains unclear. We describe a 64-year-old man with severe bone loss and persistent secondary hyperparathyroidism (SHPT) after renal transplantation, whose condition failed to respond to conventional pharmacologic or surgical interventions. He underwent parathyroidectomy with left forearm autograft of crushed tiny parathyroid gland (PTG) particles. However, the autografted PTGs became swollen and caused persistent SHPT in spite of two additional parathyroidectomies of the left forearm. A single subcutaneous administration of DMAb induced hypocalcemia, which was corrected by calcium supplementation and high-dose calcitriol. Eventually, combination therapy with DMAb and calcitriol led to a decline in the patient's elevated serum parathyroid hormone levels, normalization of laboratory markers of bone metabolism, and improvement in bone mineral density in a short period of time. To the best of our knowledge, this is the first case report of severe bone loss with persistent SHPT in a renal transplant recipient effectively treated with the combination therapy of DMAb and vitamin D (VD). Although DMAb itself exerts no direct effects on PTGs, the DMAb treatment improved the patient's bone loss. In addition, administration of DMAb allowed for high-dose VD therapy which ultimately controlled SHPT and prevented DMAb-induced hypocalcemia. Therefore, this combination therapy might be a reasonable therapeutic strategy to reverse severe bone loss due to therapy-resistant SHPT in patients with CKD.