A Randomized Study Comparing Parathyroidectomy with Cinacalcet for Treating Hypercalcemia in Kidney Allograft Recipients with Hyperparathyroidism

Calcimimetics or parathyroidectomy for kidney transplant recipients: is there still a question? a systematic review, meta-analysis and trial sequential analysis

PURPOSE

Secondary hyperparathyroidism is one of the most common complications of chronic kidney disease. The optimal treatment for chronic kidney disease nowadays is kidney transplant. Nonetheless, hyperparathyroidism does not always resolve after transplantation leading to tertiary hyperparathyroidism. The management of tertiary hyperparathyroidism can be either medical (calcimimetics) or surgical (parathyroidectomy). The aim of this study is to compare the medical and surgical treatment in terms of control of hyperparathyroidism and long-term implications on kidney graft function.

METHODS

We carried out a systematic review and meta-analysis of relevant studies up to March 2024 on MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and Scopus databases. We compared the parathyroid hormone, calcium, creatinine and estimated glomerular filtration rate between the groups of patients that were treated with parathyroidectomy and those that were treated with calcimimetcs. Subsequently, we performed a trial sequential analysis to corroborate our findings.

RESULTS

Four studies were included in the final analysis with a total number of 247 patients. Parathyroidectomy resulted in a greater decrease in parathyroid hormone and calcium levels (WMD 149.37, CI 95% 126.81-171.93, p < 0.0001 and WMD 0.7, CI 95% 0.45-0.96, p < 0.0001 respectively) but there was no difference between the surgical and medical management groups in the creatinine and eGFR levels (CI 95%, -0.62-0.17, p = 0.27 and CI 95%, -8.06 - 20.54 p = 0.39). The trial sequential analysis corroborated these findings.

CONCLUSION

Parathyroidectomy is more effective in controlling hyperparathyroidism in kidney transplant recipients, as it leads to a greater decrease in parathyroid hormone and calcium levels. However, there is no difference in the long-term function of the kidney graft, as the creatinine and estimated glomerular filtration values were similar in the surgical and medical management groups.

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.

Preoperative Calcimimetic Treatment may Prevent Serum Creatinine Elevation after Parathyroidectomy in Kidney Transplant Recipients: A Retrospective Cohort Study

BACKGROUND

Hyperparathyroidism (HPT) often persists after successful kidney transplantation (KTx). Although parathyroidectomy (PTx) is an effective treatment option for post-KTx HPT, it is associated with postoperative elevation of serum creatinine levels. We hypothesized that pre-PTx calcimimetic treatment could alleviate the post-PTx increase in serum creatinine levels.

METHODS

This retrospective cohort study enrolled KTx patients who underwent initial PTx between 2004 and 2023. Patients' background characteristics and laboratory data were investigated. The primary outcome was a change in the estimated glomerular filtration rate (eGFR). The cohort was divided into 2 groups based on the presence of pre-PTx calcimimetic treatment. Multivariate linear regression analysis assessed the association between calcimimetic treatment and percent eGFR 1 week after PTx.

RESULTS

Of the 77 KTx patients who underwent PTx, 28 were treated with pre-PTx calcimimetics (calcimimetic group), and the others were not (noncalcimimetic group). Compared with the noncalcimimetic group, the calcimimetic group had lower serum calcium levels before PTx (10.3 vs 11.2 mg/dL, P < .001) and a significantly higher percentage of eGFR 1 week after PTx (95.1% vs 81.5%, P < .001). According to the multivariate analysis, pre-PTx calcimimetic treatment was positively associated with percent eGFR (regression coefficient estimate, 13.76; 95% confidence interval, 7.02-20.50; P < .001) 1 week after PTx.

CONCLUSION

Pre-PTx calcimimetic treatment may prevent post-PTx elevation of serum creatinine levels in KTx patients.

Surgical outcomes of parathyroidectomy for pre-kidney transplantation versus post-kidney transplantation patients

BACKGROUND

Hyperparathyroidism (HPT) is common in end-stage kidney disease and resolves in less than half of kidney transplant (KT) recipients. The ideal timing of parathyroidectomy (PTX), before or after KT, remains unclear. We sought to understand differences in morbidity and mortality after PTX pre-KT and post-KT.

METHODS

We identified adult patients who underwent PTX pre-KT or post-KT between 2012 and 2021 utilizing the National Surgical Quality Improvement Program database. Demographics, clinical characteristics, morbidity, and mortality were compared. Adjusted logistic regression with propensity score weighting assessed odds of 30-day composite morbidity, major adverse cardiovascular events (MACE), readmission, and mortality.

RESULTS

We identified 1972 patients who underwent PTX pre-KT and 541 patients who underwent PTX post-KT. Post-KT HPT patients were older (mean age 53.9 v 48.2 and p < 0.01) and more commonly White (45.3% v 32.3% and p < 0.01) and diabetic (30.0% v 18.5% and p < 0.01). In comparison, pre-KT HPT patients were more commonly Black (53.2% v 30.1%), had American Society of Anesthesiologists (ASA) class 3-4 (98.0% v 89.6% and p < 0.01), chronic obstructive pulmonary disease (4.2% v 1.5% and p < 0.01), and congestive heart failure (4.4% v 1.1% and p < 0.01). After adjusting for confounders, patients pre-KT had 1.72-fold increased odds of morbidity (95% confidence interval [CI]: 1.13-2.61), 8.39-fold increased odds of MACE (95% CI: 1.13-62.18), and 2.07-fold increased odds of readmission (95% CI: 1.38-3.10). There was no difference in mortality or risk of infections.

CONCLUSIONS

Patients who underwent PTX prior to KT were at significantly increased risk for 30-day morbidity and MACE, but no different odds of mortality compared to PTX after KT. This can help inform decision-making regarding timing of PTX in patients with HPT.

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.

Subtotal Versus Total Parathyroidectomy for the Management of Tertiary Hyperparathyroidism: A Systematic Literature Review and Meta-Analysis of Optimal Surgical Modality

Background: Surgery is the definitive treatment option for tertiary hyperparathyroidism (THPT), however, the optimal surgical approach remains unclear. We aimed to compare total parathyroidectomy (PTX) with auto-transplantation vs subtotal PTX for THPT through a systematic review and meta-analysis.Methods: PubMed, Embase, and Web of Science were searched for studies comparing outcomes of total vs subtotal PTX for THPT. A total of 28 studies (n = 1000 patients) met the inclusion criteria.Results: The mean age was 46.5 years and 53% were female. The proportion of females (59% vs 49%) was higher in the total PTX with auto-transplantation cohort (P = .008). Both procedures had similar preoperative calcium and PTH levels. Postoperative and 6-month calcium and PTH were also comparable between groups, except transiently higher post-operative PTH in the total PTX with auto-transplantation cohort (P = .03). Hypercalcemia cure rates were 98%-100% with no difference between surgical techniques (P = .67). Safety profiles were comparable and low.Conclusions: Total PTX with auto-transplantation and subtotal PTX yield similar efficacy and safety for THPT, with no significant differences in cure rates, recurrence, complications, or biochemical control.

Timing of parathyroidectomy after kidney transplantation: A cost-effectiveness analysis

INTRODUCTION

Parathyroidectomy is the definitive treatment for tertiary hyperparathyroidism post-kidney transplantation. However, cinacalcet-based medical management is increasingly used as an alternative. The financial consequences of each treatment remain unclear. We aimed to identify the most cost-effective strategy for managing hyperparathyroidism from the kidney transplantation recipient's perspective.

METHODS

We constructed a patient-level discrete event simulation model to compare parathyroidectomy and cinacalcet-based medical management. The effects of hyperparathyroidism on allograft survival and all-cause mortality were considered in the discrete event simulation model with a time horizon of 15 years. Our base case was a 55-year-old kidney transplantation recipient with persistent hyperparathyroidism and hypercalcemia. The primary outcome was the cost-effectiveness measured by cost per quality-adjusted life years.

RESULTS

The monthly out-of-pocket cost of cinacalcet ranged from $12 to $288, depending on insurance coverage, with a base case cost of $150. Our base case analysis showed that parathyroidectomy was the dominant treatment with lesser cost ($1,315 vs $7,147) and greater effectiveness (3.17 quality-adjusted life years and 2.92 quality-adjusted life years) than cinacalcet. One-way sensitivity analysis on the cinacalcet treatment duration showed that parathyroidectomy became more cost-effective at 9 months. Two-way sensitivity analysis on the cost of cinacalcet and the duration of treatment with cinacalcet showed that as the monthly cost of cinacalcet increases, the expense of cinacalcet-based medical management quickly exceeds the cost of parathyroidectomy.

CONCLUSION

Parathyroidectomy becomes more cost-effective for kidney transplantation recipients with tertiary hyperparathyroidism when they require cinacalcet-based medical management for more than 9 months. As part of shared decision-making, it is important to discuss the financial costs involved in treating tertiary hyperparathyroidism.

Outcome of surgical parathyroidectomy for tertiary hyperparathyroidism in kidney transplant recipients: tertiary hyperparathyroidism should not be ignored, for the sake of precious allografts

Tertiary hyperparathyroidism is a complication of kidney transplantation. This complicated condition carries over from the dialysis period and varies according to the function of the transplanted allograft. Treatments include pharmacotherapy (mainly using calcimimetics) and parathyroidectomy, but calcimimetics are currently not covered by the national insurance system in Japan. Two types of parathyroidectomy can be performed: subtotal parathyroidectomy; and total parathyroidectomy with partial autograft. Both types can be expected to improve hypercalcemia. Concerns about the postoperative deterioration of allograft function are influenced by preoperative allograft function, which is even more likely to be affected by early surgery after kidney transplantation. In general, transient deterioration of allograft function after surgery is not expected to affect graft survival rate in the medium to long term. Tertiary hyperparathyroidism in kidney transplant recipients negatively impacts allograft and patient survival rates, and parathyroidectomy can be expected to improve prognosis in both kidney recipients and dialysis patients. However, studies offering high levels of evidence remain lacking.

Effect of Parathyroidectomy After Renal Transplantation on Grafted Kidney Function Within One Year: A Meta-Analysis

OBJECTIVE

Secondary hyperparathyroidism (sHPT) is a common symptom of chronic kidney disease (CKD), and at the time of transplantation, more than two-thirds of patients with end-stage renal disease have secondary hyperparathyroidism. After kidney transplantation, parathyroid function is normalized in some kidney transplant recipients, but up to 50% of kidney transplant recipients develop tertiary hyperparathyroidism (tHPT) 1 year after kidney transplantation. The effect of parathyroidectomy on the grafts is currently unclear; thus, we conducted a meta-analysis of relevant studies to evaluate changes in graft function 1 year after parathyroidectomy, aiming to assess the procedure's safety in renal transplant recipients.

METHODS

A thorough exploration was conducted across Embase, PubMed, Web of Science, and the Cochrane Library databases to gather pertinent literature spanning from January 1, 2000, to December 31, 2023. The search criteria encompassed terms such as "kidney transplantation," "parathyroidectomy," and "hyperparathyroidism."

RESULTS

Twelve studies were scrutinized to assess alterations in graft functionality at 1, 3, 6, and 12 months postparathyroidectomy. The meta-analysis unveiled a notable decline in overall glomerular filtration rate and a concurrent elevation in serum creatinine 1 year postparathyroidectomy, signifying an impairment in graft function compared to the preoperative phase. Significant heterogeneity was observed among the studies.

CONCLUSION

Following parathyroidectomy in renal transplant recipients 1 year postsurgery, calcium and parathyroid hormone levels normalized. Nonetheless, there was evident impairment in graft function and an elevated risk of graft loss. Hence, the safety of parathyroidectomy in patients with secondary hyperparathyroidism postrenal transplantation necessitates meticulous consideration.

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.

A novel nomogram for predicting the risk of persistent hyperparathyroidism after kidney transplantation

PURPOSE

Persistent hyperparathyroidism (PTHPT) in kidney transplant recipients is associated with bone loss, graft dysfunction and cardiovascular mortality. There is no clear consensus on the management of PTHPT. Accurate risk prediction of the disease is needed to support individualized treatment decisions. We aim to develop a useful predictive model to provide early intervention for hyperparathyroidism in these patients.

METHODS

We retrospectively analyzed 263 kidney transplantations in the urology department of China-Japan Friendship Hospital from January 2018 to December 2022. The overall cohort was randomly assigned 70% of the patients to the training cohort and 30% to the validation cohort. Univariate and multivariate logistic regression analyses were used to identify independent risk factors for PTHPT and to construct the predictive model. This model was assessed regarding discrimination, consistency, and clinical benefit.

RESULTS

The occurrence of PTHPT was 25.9% (68 out of 263 patients) in this study. Dialysis duration, postoperative 3-month intact parathyroid hormone (iPTH), 3-month corrected calcium (cCa), and 3-month phosphorus (P) are independent risk factors for the development of PTHPT. The nomogram showed good discrimination with the area under the curve (AUC) value of 0.926 in the training cohort and 0.903 in the validation cohort. The calibration curve and decision curve also showed that the model was well-evaluated.

CONCLUSION

We developed a validated nomogram model to predict PTHPT after kidney transplantation. This can help the clinic prevent and control PTHPT early and improve patients' prognosis.

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.

Multiple fractures due to hungry bone syndrome following parathyroidectomy: a clinical case report and review of literature

BACKGROUND

Hungry bone syndrome (HBS) is defined as prolonged hypocalcemia caused by a sudden decrease in parathyroid hormone (PTH) levels after parathyroidectomy (PTX). Multiple fractures after PTX due to HBS in an end-stage renal disease (ESRD) patient on chronic hemodialysis (HD) are challenging and rare medical conditions presented in this study.

CASE PRESENTATION

A 42-year-old ESRD patient on HD 3 times a week presented to Shariati Hospital, Tehran, Iran, complaining of worsening bone pain and loss of appetite. Laboratory data revealed an intact parathyroid hormone (iPTH) concentration of 2500 pg/mL, an alkaline phosphatase (Alp) level of 4340 IU/L, a phosphorus (P) level of 9 mg/dL, and a calcium (Ca) concentration of 7.2 mg/dL. Sestamibi scintigraphy revealed parathyroid adenoma. The findings suggested tertiary hyperparathyroidism (HPT-III), and the patient was scheduled for total PTX. Approximately one month after surgery, the patient was referred due to convulsions, leg mobility problems, and worsening bone pain. There was bilateral femoral ecchymosis. The Ca concentration was 5.8 mg/dL, and radiological evaluations revealed multiple skeletal fractures. HBS after PTX was suggested for this patient. After several days of hospitalization, he suffered subcutaneous emphysema followed by rib fractures and passed away.

CONCLUSIONS

Multiple fractures after PTX due to HBS following HPT-III in ESRD patients are rare and demanding, highlighting the necessity of timely diagnosis and management of patients with HPT-III. Severe hypocalcemia following PTX can cause skeletal disorders. However, the surgical treatment of parathyroid adenomas may be more important than the risk of complications associated with bone health.

Metastatic Calcification in Allograft Kidney Due to Persistent Secondary Hyperparathyroidism: A Rare Cause of Graft Dysfunction

Successful kidney transplant corrects mineral and bone disorderto a large extent; however, disorders can persistin up to 80% ofrecipients.We describe a case of persistent hyperparathyroidism with graft dysfunction and metastatic calcification in graft biopsy. A 48-yearold renal transplant recipient developed graft dysfunction 3 weeks after kidney transplant. During pretransplant workup, the recipient was found to have severe secondary hyperparathyroidism (intact parathyroid hormone level of 2000 pg/mL), which was managed and well controlled before transplant. Graft dysfunction was evaluated using algorithmic approach. Prerenal causes, tacrolimus toxicity, and infections were ruled out. Graft biopsy revealed several foci of tubular and parenchyma calcific deposits (microcalcinosis) with tubular injury. The patient was restarted on medical management of hyperparathyroidism, and he showed improvement over 6 weeks, along with creatinine level returning to nadir value. Vascular and graft calcification is an independent predictor of long-term graftfunction and overall mortality. This report describes the challenges that we faced in diagnosis and management of persistent hyperparathyroidism, as no randomized controlled trials and guidelines are available.

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.

Pretransplant Parathyroidectomy in Patients with Severe Secondary Hyperparathyroidism and Long-Term Effectiveness After Kidney Transplantation

Kidney transplantation (KT) is the best option for patients with end-stage renal disease, but recipients still have legacy bone mineral disease from the pretransplant period, especially patients with severe secondary hyperparathyroidism (sHPT). Patients who had severe sHPT and underwent KT were analyzed retrospectively. Two groups were identified (patients with severe sHPT who had parathyroidectomy or calcimimetic before KT). Bone mineral density (BMD) was measured in the first year and last follow-up at the femoral neck, total hip, and lumbar spine using the dual-energy X-ray absorptiometry (DXA). Persistent hyperparathyroidism (perHPT) incidence was significantly higher in the calcimimetic group (75% vs. 40%, p=0.007). In patients with parathyroidectomy, BMDs were higher at femoral neck (0.818±0.114 vs. 0.744±0.134, p=0.04) and lumbar spine (1.005±0.170 vs. 0.897±0.151, p=0.01) at the first assessment. The BMD comparison between patients treated with parathyroidectomy and calcimimetic found a significant difference only in the femoral neck at second evaluation (0.835±0.118 vs. 0.758±0.129; p=0.03). In multivariate, linear regression revealed a positive association between the last BMD of the femoral neck with body mass index (CC: 0.297, 95% CI, 0.002-0.017) and parathyroidectomy (CC: 0.319, 95% CI, 0.021-0.156). Parathyroidectomy is associated with a significantly better femoral neck BMD and a lower incidence of perHPT in patients with severe sHPT.

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.

Pre-Transplant Calcimimetic Use and Dose Information Improves the Accuracy of Prediction of Tertiary Hyperparathyroidism after Kidney Transplantation: A Retrospective Cohort Study

Tertiary hyperparathyroidism (THPT) is characterized by elevated parathyroid hormone and serum calcium levels after kidney transplantation (KTx). To ascertain whether pre-transplant calcimimetic use and dose information would improve THPT prediction accuracy, this retrospective cohort study evaluated patients who underwent KTx between 2010 and 2022. The primary outcome was the development of clinically relevant THPT. Logistic regression analysis was used to evaluate pre-transplant calcimimetic use as a determinant of THPT development. Participants were categorized into four groups according to calcimimetic dose, developing two THPT prediction models (with or without calcimimetic information). Continuous net reclassification improvement (CNRI) and integrated discrimination improvement (IDI) were calculated to assess ability to reclassify the degree of THPT risk by adding pre-transplant calcimimetic information. Of the 554 patients, 87 (15.7%) developed THPT, whereas 139 (25.1%) received pre-transplant calcimimetic treatment. Multivariate logistic regression analysis revealed that pre-transplant calcimimetic use was significantly associated with THPT development. Pre-transplant calcimimetic information significantly improved the predicted probability accuracy of THPT (CNRI and IDI were 0.91 [p < 0.001], and 0.09 [p < 0.001], respectively). The THPT prediction model including pre-transplant calcimimetic information as a predictive factor can contribute to the prevention and early treatment of THPT in the era of calcimimetics.

The Molecular Mechanisms Underlying the Systemic Effects Mediated by Parathormone in the Context of Chronic Kidney Disease

Chronic kidney disease (CKD) stands as a prominent non-communicable ailment, significantly impacting life expectancy. Physiopathology stands mainly upon the triangle represented by parathormone-Vitamin D-Fibroblast Growth Factor-23. Parathormone (PTH), the key hormone in mineral homeostasis, is one of the less easily modifiable parameters in CKD; however, it stands as a significant marker for assessing the risk of complications. The updated "trade-off hypothesis" reveals that levels of PTH spike out of the normal range as early as stage G2 CKD, advancing it as a possible determinant of systemic damage. The present review aims to review the effects exhibited by PTH on several organs while linking the molecular mechanisms to the observed actions in the context of CKD. From a diagnostic perspective, PTH is the most reliable and accessible biochemical marker in CKD, but its trend bears a higher significance on a patient's prognosis rather than the absolute value. Classically, PTH acts in a dichotomous manner on bone tissue, maintaining a balance between formation and resorption. Under the uremic conditions of advanced CKD, the altered intestinal microbiota majorly tips the balance towards bone lysis. Probiotic treatment has proven reliable in animal models, but in humans, data are limited. Regarding bone status, persistently high levels of PTH determine a reduction in mineral density and a concurrent increase in fracture risk. Pharmacological manipulation of serum PTH requires appropriate patient selection and monitoring since dangerously low levels of PTH may completely inhibit bone turnover. Moreover, the altered mineral balance extends to the cardiovascular system, promoting vascular calcifications. Lastly, the involvement of PTH in the Renin-Angiotensin-Aldosterone axis highlights the importance of opting for the appropriate pharmacological agent should hypertension develop.

Association of Coronary Calcium Score on Cardiac PET During Pre-Kidney Transplant Assessment with Persistent Hyperparathyroidism: A Retrospective Study

BACKGROUND Secondary hyperparathyroidism and coronary calcifications are common complications in chronic kidney disease. However, the relation between coronary calcium score (CCS) and persistent hyperparathyroidism (pHPT) after kidney transplantation (KT) remains unknown. MATERIAL AND METHODS This was a single-center retrospective study of KT candidates from January 2017 to May 2020. We collected patients' demographics, cardiovascular (CV) risk factors, and the findings of pre-KT CV imaging. We also collected parathyroid hormone (PTH) values before KT, at 1-6 months, 6-12 months, and 12-24 months after KT. We defined pHPT as PTH ≥25.5 pmol/L after 12 months post-KT. RESULTS A total of 111 KT recipients (KTRs) with a mean age of 50.4 years were included, of which 62.2% were men and 77.5% were living-donor KTRs. Dialysis modality used before KT was peritoneal dialysis in 9.9% and hemodialysis in 82.9%. Dialysis vintage was 3±2.9 years. The prevalence of pHPT was 24.3% (n=27), and the prevalence of severe coronary calcifications (CCS >400 Agatston units) was 19.8% (n=22). PTH values at baseline, 1-6 months, 6-12 months, and 12-24 months were not different among between CCS >400 or CCS <400 groups. However, pHPT after KT was significantly more prevalent in KTRs with severe CCS (37% vs 14.3%, p=0.014). Severe CCS was associated with less improvement of PTH values after KT (r=0.288, p=0.020). Otherwise, the findings of cardiac PET and coronary angiogram were not significantly different between pHPT and non-pHPT patients. CCS >400 was independently associated with pHPT after transplant (aOR=18.8, P=0.012). CONCLUSIONS Severe CCS on pre-KT cardiac assessment is associated with pHPT after KT.

US-guided Percutaneous Radiofrequency Ablation for Secondary Hyperparathyroidism: Long-term Outcomes and Prognostic Factors

Background Although favorable outcomes have been reported with radiofrequency ablation (RFA) for secondary hyperparathyroidism (SHPT), the long-term efficacy remains insufficiently investigated. Purpose To evaluate the long-term efficacy and safety of US-guided percutaneous RFA in patients with SHPT undergoing dialysis and to identify possible predictors associated with treatment failure. Materials and Methods This retrospective study included consecutive patients with SHPT with at least one enlarged parathyroid gland accessible for RFA who were undergoing dialysis at seven tertiary centers from May 2013 to July 2022. The primary end point was the proportion of patients with parathyroid hormone (PTH) levels less than or equal to 585 pg/mL at the end of follow-up. Secondary end points were the proportion of patients with normal calcium and phosphorus levels, the technical success rate, procedure-related complications, and improvement in self-rated hyperparathyroidism-related symptoms (0-3 ranking scale). The Wilcoxon signed rank test and generalized estimating equation model were used to evaluate treatment outcomes. Univariable and multivariable regression analyses identified variables associated with treatment failure (recurrent or persistent hyperparathyroidism). Results This study included 165 patients (median age, 51 years [IQR, 44-60 years]; 92 female) and 582 glands. RFA effectively reduced PTH, calcium, and phosphorus levels, with targeted ranges achieved in 78.2% (129 of 165), 72.7% (120 of 165), and 60.0% (99 of 165) of patients, respectively, at the end of follow-up (mean, 51 months). For the RFA sessions, the technical success rate was 100% (214 of 214). Median symptom scores (ostealgia, arthralgia, pruritus) decreased (all P < .001). Regarding complications, only hypocalcemia (45.8%, 98 of 214) was common. Treatment failure occurred in 36 patients (recurrent [n = 5] or persistent [n = 31] hyperparathyroidism). The only potential independent predictor of treatment failure was having less than four treated glands (odds ratio, 17.18; 95% CI: 4.34, 67.95; P < .001). Conclusion US-guided percutaneous RFA was effective and safe in the long term as a nonsurgical alternative for patients with SHPT undergoing dialysis; the only potential independent predictor of treatment failure was a lower number (<4) of treated glands. © RSNA, 2024 Supplemental material is available for this article.

Pre-Transplant Hyperparathyroidism and Graft or Patient Outcomes After Kidney Transplantation

The impact of pre-transplant parathyroid hormone (PTH) levels on early or long-term kidney function after kidney transplantation is subject of debate. We assessed whether severe hyperparathyroidism is associated with delayed graft function (DGF), death-censored graft failure (DCGF), or all-cause mortality. In this single-center cohort study, we studied the relationship between PTH and other parameters related to bone and mineral metabolism, including serum alkaline phosphatase (ALP) at time of transplantation with the subsequent risk of DGF, DCGF and all-cause mortality using multivariable logistic and Cox regression analyses. In 1,576 kidney transplant recipients (51.6 ± 14.0 years, 57.3% male), severe hyperparathyroidism characterized by pre-transplant PTH ≥771 pg/mL (>9 times the upper limit) was present in 121 patients. During 5.2 [0.2-30.0] years follow-up, 278 (15.7%) patients developed DGF, 150 (9.9%) DCGF and 432 (28.6%) died. A higher pre-transplant PTH was not associated with DGF (HR 1.06 [0.90-1.25]), DCGF (HR 0.98 [0.87-1.13]), or all-cause mortality (HR 1.02 [0.93-1.11]). Results were consistent in sensitivity analyses. The same applied to other parameters related to bone and mineral metabolism, including ALP. Severe pre-transplant hyperparathyroidism was not associated with an increased risk of DGF, DCGF or all-cause mortality, not supporting the need of correction before kidney transplantation to improve graft or patient survival.

The Bone-Vascular Axis in Chronic Kidney Disease: From Pathophysiology to Treatment

PURPOSE OF REVIEW

This review aims to describe the pathogenic factors involved in bone-vessel anomalies in CKD which are the object of numerous experimental and clinical research.

RECENT FINDINGS

Knowledge on the pathophysiological mechanisms involved in the regulation of vascular calcification and mineral-bone disorders is evolving. Specific bone turnover anomalies influence the vascular health while recent studies demonstrate that factors released by the calcified vessels also contribute to bone deterioration in CKD. Current therapies used to control mineral dysregulations will impact both the vessels and bone metabolism. Available anti-osteoporotic treatments used in non-CKD population may negatively or positively affect vascular health in the context of CKD. It is essential to study the bone effects of the new therapeutic options that are currently under investigation to reduce vascular calcification. Our paper highlights the complexity of the bone-vascular axis and discusses how current therapies may affect both organs in CKD.

Predictive factors for persistent hypercalcemia following parathyroidectomy in patients with persistent hyperparathyroidism after kidney transplantation: a retrospective cohort study

BACKGROUND

Surgery for irreversible hyperparathyroidism is the preferred management for kidney transplant patients. The authors analyzed the factors associated with persistent hypercalcemia after parathyroidectomy in kidney transplant patients and evaluated the appropriate extent of surgery.

MATERIALS AND METHODS

The authors retrospectively analyzed 100 patients who underwent parathyroidectomy because of persistent hyperparathyroidism after kidney transplantation at a tertiary medical center between June 2011 and February 2022. Patients were divided into two groups: 22 with persistent hypercalcemia after parathyroidectomy and 78 who achieved normocalcemia after parathyroidectomy. Persistent hypercalcemia was defined as having sustained hypercalcemia (≥10.3 mg/dl) 6 months after kidney transplantation. The authors compared the biochemical and clinicopathological features between the two groups. Multivariate logistic regression analysis was used to identify potential risk factors associated with persistent hypercalcemia following parathyroidectomy.

RESULTS

The proportion of patients with serum intact parathyroid hormone (PTH) level is greater than 65 pg/ml was significantly high in the hypercalcemia group (40.9 vs. 7.7%). The proportion of patients who underwent less than subtotal parathyroidectomy was significantly high in the persistent hypercalcemia group (17.9 vs. 54.5%). Patients with a large remaining size of the preserved parathyroid gland (≥0.8 cm) had a high incidence of persistent hypercalcemia (29.7 vs. 52.6%). In the multivariate logistic regression analysis, the drop rate of intact PTH is less than 88% on postoperative day 1 (odds ratio 10.3, 95% CI: 2.7-39.1, P =0.001) and the removal of less than or equal to 2 parathyroid glands (odds ratio 6.8, 95% CI: 1.8-26.7, P =0.001) were identified as risk factors for persistent hypercalcemia.

CONCLUSION

The drop rate of intact PTH is less than 88% on postoperative day 1 and appropriate extent of surgery for controlling the autonomic function were independently associated with persistent hypercalcemia. Confirmation of parathyroid lesions through frozen section biopsy or intraoperative PTH monitoring can be helpful in preventing the inadvertent removal of a parathyroid gland and achieving normocalcemia after parathyroidectomy.

Neurorescuing effect of Cinacalcet against hypercalcemia-induced nerve injury in chronic kidney disease via TRAF2/cIAP1/KLF2/SERPINA3 signal axis

Hypercalcemia is a common complication in chronic kidney disease (CKD) and unfortunately contributes to nerve injury. This study aims to investigate the potential role and underlying mechanisms of Cinacalcet (CIN) in hypercalcemia-driven nerve injury in CKD. A CKD mouse model was first established by adenine feeding to identify the therapeutic effects of CIN. Molecules related to CIN and CKD were predicted by bioinformatics analysis and their expression in the kidney tissues of CKD mice was measured by immunochemistry. Gain- and loss-of-functions assays were performed both in vitro and in vivo to evaluate their effects on nerve injury in CKD, as reflected by Scr and BUN, and brain calcium content as well as behavior tests. CIN ameliorated hypercalcemia-driven nerve injury in CKD mice. Interactions among TRAF2, an E3-ubiquitin ligase, KLF2, and SERPINA3 were bioinformatically predicted on CIN effect. CIN restricted the ubiquitin-mediated degradation of KLF2 by downregulating TRAF2. KLF2 targeted and inversely regulated SERPINA3 to repress hypercalcemia-driven nerve injury in CKD. CIN was substantiated in vivo to ameliorate hypercalcemia-driven nerve injury in CKD mice through the TRAF2/KLF2/SERPINA3 regulatory axis. Together, CIN suppresses SERPINA3 expression via TRAF2-mediated inhibition of the ubiquitin-dependent degradation of KLF2, thus repressing hypercalcemia-induced nerve injury in CKD mice.

Resolution of Secondary Hyperparathyroidism After Kidney Transplantation and the Effect on Graft Survival

OBJECTIVE

Hyperparathyroidism (HPT) is nearly universal in patients with end-stage kidney disease. Kidney transplantation (KT) reverses HPT in many patients, but most studies have only focused on following calcium and not parathyroid hormone (PTH) levels. We sought to study the prevalence of persistent HPT post-KT at our center and its effect on graft survival.

METHODS

Patients who underwent KT from January 2015 to August 2021 were included and characterized by post-KT HPT status at the most recent follow-up: resolved (achieving normal PTH post-KT) versus persistent HPT. Those with persistent HPT were further stratified by the occurrence of hypercalcemia (normocalcemic versus hypercalcemic HPT). Patient demographics, donor kidney quality, PTH and calcium levels, and allograft function were compared between groups. Multivariable logistic regression and Cox regression with propensity score matching were conducted.

RESULTS

Of 1554 patients, only 390 (25.1%) patients had resolution of renal HPT post-KT with a mean (±SD) follow-up length of 40±23 months. The median (IQR) length of HPT resolution was 5 (0-16) months. Of the remaining 1164 patients with persistent HPT post-KT, 806 (69.2%) patients had high PTH and normal calcium levels, while 358 (30.8%) patients had high calcium and high PTH levels. Patients with persistent HPT had higher parathyroid hormone (PTH) at the time of KT [403 (243-659) versus 277 (163-454) pg/mL, P <0.001] and were more likely to have received cinacalcet treatment before KT (34.9% vs. 12.3%, P <0.001). Only 6.3% of patients with persistent HPT received parathyroidectomy. Multivariable logistic regression showed race, cinacalcet use pre-KT, dialysis before KT, receiving an organ from a deceased donor, high PTH, and calcium levels at KT were associated with persistent HPT post-KT. After adjusting for patient demographics and donor kidney quality by propensity score matching, persistent HPT (HR 2.5, 95% CI 1.1-5.7, P =0.033) was associated with a higher risk of allograft failure. Sub-analysis showed that both hypercalcemic HPT (HR 2.6, 95% CI 1.1-6.5, P =0.045) and normocalcemic HPT (HR 2.5, 95% CI 1.3-5.5, P =0.021) were associated with increased risk of allograft failure when compared with patients with resolved HPT.

CONCLUSION

Persistent HPT is common (75%) after KT and is associated with a higher risk of allograft failure. PTH levels should be closely monitored after kidney transplantation so that patients with persistent HPT can be treated appropriately.

Recommendations of the Spanish Society of Nephrology for the management of mineral and bone metabolism disorders in patients with chronic kidney disease: 2021 (SEN-MM)

As in 2011, when the Spanish Society of Nephrology (SEN) published the Spanish adaptation to the Kidney Disease: Improving Global Outcomes (KDIGO) universal Guideline on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), this document contains an update and an adaptation of the 2017 KDIGO guidelines to our setting. In this field, as in many other areas of nephrology, it has been impossible to irrefutably answer many questions, which remain pending. However, there is no doubt that the close relationship between the CKD-MBD/cardiovascular disease/morbidity and mortality complex and new randomised clinical trials in some areas and the development of new drugs have yielded significant advances in this field and created the need for this update. We would therefore highlight the slight divergences that we propose in the ideal objectives for biochemical abnormalities in the CKD-MBD complex compared to the KDIGO suggestions (for example, in relation to parathyroid hormone or phosphate), the role of native vitamin D and analogues in the control of secondary hyperparathyroidism and the contribution of new phosphate binders and calcimimetics. Attention should also be drawn to the adoption of important new developments in the diagnosis of bone abnormalities in patients with kidney disease and to the need to be more proactive in treating them. In any event, the current speed at which innovations are taking place, while perhaps slower than we might like, globally drives the need for more frequent updates (for example, through Nefrología al día).

Factors Associated With Persistent Post-transplant Hyperparathyroidism After Index Renal Transplantation

INTRODUCTION

Secondary hyperparathyroidism (SHP) is common in end-stage renal disease and may progress to persistent post-transplant hyperparathyroidism (PTHP) following renal transplantation (RT). We sought to describe the frequency and determine factors associated with the incidence of PTHP for patients undergoing RT at a single institution that restricts RT for patients with uncontrolled SHP with a parathyroid hormone (PTH) of >800pg/mL at time of initial transplant evaluation.

METHODS

We conducted a single-institution retrospective study of adults undergoing index RT from 2012 to 2020 who had a calcium and PTH level within 12 mo prior to RT and at least 6 mo following RT. PTHP was defined as calcium of >10 mg/dL with an elevated PTH > 88pg/mL at six or more months following RT. Univariate analysis and multivariable logistic regression were performed for factors associated with developing PTHP.

RESULTS

We identified 1110 patients with RT, 65 were excluded for prior RT, 549 did not have a pre-RT and post-RT calcium, and PTH laboratories for inclusion, yielding 496 for analysis. Following RT, 39 patients (7.9%) developed PTHP, compared to those who did not develop PTHP; these patients had significantly higher pre-RT PTH, pre-RT calcium, and frequency of calcimimetic therapy. In multivariable logistic regression factors significantly associated with PTHP were pre-RT calcium of more than 10 mg/dL with an odds ratio (OR) of 3.57 (95% confidence interval [CI] 1.52-8.39, P = 0.003) and pre-RT calcimimetic therapy with an OR 1.30 (95% CI 1.06-2.85, P = 0.041). Compared with patients who had a pre-RT PTH of less than 200 pg/mL, a PTH of 200-399 pg/mL increased risk of PTHP with an OR of 4.52 (95% CI 1.95-21.5, P = 0.048) and a PTH of > 400 pg/mL increased risk of PTHP with an OR of 7.17 (95% CI 1.47-34.9, P = 0.015). In this cohort, 11 patients (28.2%) with PTHP underwent parathyroidectomy (PTx) at a mean of 1.4 y post-RT (standard deviation 0.87).

CONCLUSIONS

For patients required to have a PTH < 800pg/mL for initial transplant candidacy, the subsequent incidence of PTHP is relatively low at 7.9%. Risk factors for PTHP include higher pre-RT calcium and PTH levels and pre-RT calcimimetic therapy. PTx remains underused in the treatment of PTHP. Further study is warranted to determine the optimal PTH cutoff for transplant candidacy and recommendation for PTx in patients requiring calcimimetic therapy for SHP.

18F-Fluorocholine PET/CT Compared with Current Imaging Procedures for Preoperative Localization of Hyperfunctioning Parathyroids in Patients with Chronic Kidney Disease

Hyperparathyroidism (HPT) in patients with chronic kidney disease (CKD) includes secondary (sHPT) and tertiary hyperparathyroidism (tHPT). Considering that the role of preoperative imaging in the clinical setting is controversial, in the present study we have retrospectively compared pre-surgical diagnostic performances of ¹⁸F-Fluorocholine (¹⁸F-FCH) PET/CT, cervical ultrasonography (US), parathyroid scintigraphy, and 4D-CT in a group of 30 patients with CKD and HPT (18/12 sHPT/tHPT), 21 CKD G5 including 18 in dialysis, and 9 kidney transplant recipients. All patients underwent ¹⁸F-FCH, and 22 had cervical US, 12 had parathyroid scintigraphy, and 11 had 4D-CT. Histopathology was the gold standard. Seventy-four parathyroids were removed: 65 hyperplasia, 6 adenomas, and 3 normal glands. In the whole population, in a per gland analysis, ¹⁸F-FCH PET/CT was significantly more sensitive and accurate (72%, 71%) than neck US (25%, 43%), parathyroid scintigraphy (35%, 47%), and 4D-CT (40%, 47%). The specificity of ¹⁸F-FCH PET/CT (69%) was lower than that of neck US (95%) and parathyroid scintigraphy (90%), without, however, achieving significance. ¹⁸F-FCH PET/CT was more accurate than all other diagnostic techniques when sHPT and tHPT patients were considered separately. ¹⁸F-FCH PET/CT sensitivity was significantly higher in tHPT (88%) than in sHPT (66%). Three ectopic hyperfunctioning glands (in three different patients) were all detected by ¹⁸F-FCH PET/CT, two by parathyroid scintigraphy, and none by cervical US and 4D-CT. Our study confirms that ¹⁸F-FCH PET/CT is an effective preoperative imaging option in patients with CKD and HPT. These findings may be of greater importance in patients with tHPT (who could benefit from minimally invasive parathyroidectomy) than in patients with sHPT, who often undergo bilateral cervicotomy. In these cases, preoperative ¹⁸F-FCH PET/CT may be helpful in locating ectopic glands and may guide the surgical choice for gland preservation.

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.

Effects of Cinacalcet on Post-transplantation Hypercalcemia and Hyperparathyroidism in Adult Kidney Transplant Patients: A Single-Center Experience

OBJECTIVE

Secondary hyperparathyroidism may manifest as hypercalcemia in the post-transplant period. The classical treatment method is parathyroidectomy and the alternative is oral cinacalcet, a calcimimetic agent therapy. We retrospectively investigated the effect of cinacalcet therapy on kidney and patient survival in these patients.

MATERIALS AND METHODS

In our single-center, retrospective, observational study, files of 934 patients who underwent renal transplantation in our unit between 2008 and 2022 were reviewed. A total of 23 patients were started on cinacalcet for the treatment of hypercalcemia (calcium > 10.3 mg/dl) and parathyroid hormone (PTH) elevation (>65 pg/ml). Patients with calcium < 10.3 mg/dl and PTH > 700 pg/ml at any time in the follow-up after renal transplantation were included in the study. In addition, the demographic data of the patients, baseline creatine, calcium, phosphorus, and PTH levels at the time of hypercalcemia, parathyroid ultrasonography, parathyroid scintigraphy, creatinine, calcium, phosphorus, and PTH levels in the last controls, and survival status were evaluated.

RESULTS

 The mean age of 23 patients included in the study was 52.7 ± 11 years (minimum: 32; maximum: 66). Of the patients, 16 (69.6%) were male, and 15 (65.2%) were transplanted from a living donor. Parathyroid scintigraphic revealed adenoma in three (13%) patients, hyperplasia in five patients (21.7%), and no involvement in 15 patients (65.2%). Cinacalcet treatment was initiated at a median of 33 months (interquartile range (IQR) = 13-96) after the kidney transplant operation. There was no graft loss in the patients during the follow-up period. Twenty-two patients (95.7%) were alive, and one patient died. The calcium level of the patients decreased from 11.3 ± 0.64 mg/dl to 9.98 ± 0.78 mg/dl (p = 0.001) after cinacalcet treatment. Phosphorus values increased from 2.7 ± 0.65 mg/dl to 3.10 ± 0.65 mg/dl (p = 0.004). On the other hand, there was no significant difference in PTH levels between the initial and final controls (285 (IQR = 150-573) vs. 260 pg/ml (IQR = 175-411), p = 0.650). Also, creatinine levels were similar (1.2 ± 0.38 vs. 1.24 ± 0.48 mg/dl, p = 0.43). Despite cinacalcet treatment, calcium levels did not decrease in eight patients. Complications such as renal dysfunction and pathological fracture did not develop in these patients.

CONCLUSIONS

It seems that cinacalcet treatment is a suitable option for patients with hypercalcemia and/or hyperparathyroidism with low drug interactions and good biochemical control after renal transplantation.

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.

Missed Opportunities to Diagnose and Treat Tertiary Hyperparathyroidism After Transplant

INTRODUCTION

Tertiary hyperparathyroidism (3HPT) is common after renal transplant. However, guidelines for diagnosis are not clear and few patients are treated surgically. This study aims to determine rates of diagnosis and treatment of 3HPT in renal transplant patients with hypercalcemia.

MATERIALS AND METHODS

This retrospective chart review identified all renal transplant recipients at a single tertiary care institution between 2011 and 2021. Patients with post-transplant hypercalcemia (> 10.2 mg/dL) were identified. The time in months of index hypercalcemia was noted. Measurement of parathyroid hormone (PTH) levels after index hypercalcemia was determined and noted as elevated if > 64 pg/mL at least 6 mo after transplant. Documentation of symptoms of hyperparathyroidism, a diagnosis of hyperparathyroidism in the electronic medical record, and medical or surgical management of patients with classic 3HPT (elevated calcium and PTH) were determined.

RESULTS

Of 383 renal transplant recipients, hypercalcemia was identified in 132 patients. The majority of hypercalcemic patients had PTH levels measured (127, 96.2%). PTH was elevated in 109 (82.6%). Among the 109 patients with classic 3HPT, 54 (49.5%) had a documented diagnosis of hyperparathyroidism in the electronic medical record (P = 0.01). Kidney stones or abnormal DEXA scan were present in 16 (14.7%) and 18 (16.5%), respectively. Most patients were managed non-surgically (101, 92.6%); calcimimetics were prescribed for 42 (38.5%, P = 0.01). Eight (7.3%) patients with classic 3HPT were referred to a surgeon (P = 0.35); all were initially prescribed calcimimetics (P = 0.001).

CONCLUSIONS

3HPT is underdiagnosed in patients with elevated calcium and PTH levels post-transplant. A significant percentage of these patients go without surgical referral and curative treatment.

Ultrasound-guided microwave ablation for tertiary hyperparathyroidism in patients with renal transplantation

OBJECTIVE

To explore the safety and efficacy of ultrasound-guided microwave ablation (MWA) for tertiary hyperparathyroidism (THPT) in patients with renal transplantation (RT).

METHODS

In total, fifteen patients with THPT after renal transplantation who underwent MWA were enrolled in the study. The pre- and post-MWA intact parathyroid hormone (iPTH), serum calcium, phosphorus, creatinine, urea nitrogen and estimated glomerular filtration rate (eGFR) values were compared.

RESULTS

A total of 38 parathyroid hyperplastic nodules in 15 RT patients were treated with ultrasound-guided MWA. The mean (median, range) size of the hyperplastic parathyroid nodules was 11.5 mm (11 mm, 5-25 mm), and the average (median, range) ablation time was 163.5s (121 s, 44-406 s). The average levels of serum iPTH and calcium at 1 d, 7 d, 1 month, 3 months, 6 months, 1 year post-MWA and at the end of follow-up were significantly lower than those pre-MWA (all p < 0.05). Compared with the pre-MWA value (0.76 mmol/L), the serum phosphorus levels at 1 d post-MWA (0.63 mmol/L) were significantly decreased, and those at 7 d, 1 month, 3 months, 6 months, 1 year post-MWA and at the end of follow-up were significantly increased, but all were within the normal range. There was no significant difference in serum creatinine and eGFR pre-MWA and post-MWA. No major MWA-related complications occurred.

CONCLUSION

Ultrasound-guided MWA shows potential as a viable treatment for THPT in RT patients. However, further studies are required to confirm its safety and effectiveness in larger cohorts of longer duration.

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.

A roadmap to parathyroidectomy for kidney transplant candidates

Chronic kidney disease mineral and bone disorder may persist after successful kidney transplantation. Persistent hyperparathyroidism has been identified in up to 80% of patients throughout the first year after kidney transplantation. International guidelines lack strict recommendations about the management of persistent hyperparathyroidism. However, it is associated with adverse graft and patient outcomes, including higher fracture risk and an increased risk of all-cause mortality and allograft loss. Secondary hyperparathyroidism may be treated medically (vitamin D, phosphate binders and calcimimetics) or surgically (parathyroidectomy). Guideline recommendations suggest medical therapy first but do not clarify optimal parathyroid hormone targets or indications and timing of parathyroidectomy. There are no clear guidelines or long-term studies about the impact of hyperparathyroidism therapy. Parathyroidectomy is more effective than medical treatment, although it is associated with increased short-term risks. Ideally parathyroidectomy should be performed before kidney transplantation to prevent persistent hyperparathyroidism and improve graft outcomes. We now propose a roadmap for the management of secondary hyperparathyroidism in patients eligible for kidney transplantation that includes the indications and timing (pre- or post-kidney transplantation) of parathyroidectomy, the evaluation of parathyroid gland size and the integration of parathyroid gland size in the decision-making process by a multidisciplinary team of nephrologists, radiologists and surgeons.

Role of Calcimimetics in Treating Bone and Mineral Disorders Related to Chronic Kidney Disease

Renal osteodystrophy is common in patients with chronic kidney disease and end-stage renal disease and leads to the risks of fracture and extraosseous vascular calcification. Secondary hyperparathyroidism (SHPT) is characterized by a compensatory increase in parathyroid hormone (PTH) secretion in response to decreased renal phosphate excretion, resulting in potentiating bone resorption and decreased bone quantity and quality. Calcium-sensing receptors (CaSRs) are group C G-proteins and negatively regulate the parathyroid glands through (1) increasing CaSR insertion within the plasma membrane, (2) increasing 1,25-dihydroxy vitamin D3 within the kidney and parathyroid glands, (3) inhibiting fibroblast growth factor 23 (FGF23) in osteocytes, and (4) attenuating intestinal calcium absorption through Transient Receptor Potential Vanilloid subfamily member 6 (TRPV6). Calcimimetics (CaMs) decrease PTH concentrations without elevating the serum calcium levels or extraosseous calcification through direct interaction with cell membrane CaSRs. CaMs reduce osteoclast activity by reducing stress-induced oxidative autophagy and improving Wnt-10b release, which promotes the growth of osteoblasts and subsequent mineralization. CaMs also directly promote osteoblast proliferation and survival. Consequently, bone quality may improve due to decreased bone resorption and improved bone formation. CaMs modulate cardiovascular fibrosis, calcification, and renal fibrosis through different mechanisms. Therefore, CaMs assist in treating SHPT. This narrative review focuses on the role of CaMs in renal osteodystrophy, including their mechanisms and clinical efficacy.

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.

Machine Learning-Derived Integer-Based Score and Prediction of Tertiary Hyperparathyroidism among Kidney Transplant Recipients: An Integer-Based Score to Predict Tertiary Hyperparathyroidism

BACKGROUND AND OBJECTIVES

Tertiary hyperparathyroidism in kidney allograft recipients is associated with bone loss, allograft dysfunction, and cardiovascular mortality. Accurate pretransplant risk prediction of tertiary hyperparathyroidism may support individualized treatment decisions. We aimed to develop an integer score system that predicts the risk of tertiary hyperparathyroidism using machine learning algorithms.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We used two separate cohorts: a derivation cohort with the data of kidney allograft recipients (n=669) who underwent kidney transplantation at Severance Hospital, Seoul, Korea between January 2009 and December 2015 and a multicenter registry dataset (the Korean Cohort Study for Outcome in Patients with Kidney Transplantation) as an external validation cohort (n=542). Tertiary hyperparathyroidism was defined as post-transplant parathyroidectomy. The derivation cohort was split into 75% training set (n=501) and 25% holdout test set (n=168) to develop prediction models and integer-based score.

RESULTS

Tertiary hyperparathyroidism requiring parathyroidectomy occurred in 5% and 2% of the derivation and validation cohorts, respectively. Three top predictors (dialysis duration, pretransplant intact parathyroid hormone, and serum calcium level measured at the time of admission for kidney transplantation) were identified to create an integer score system (dialysis duration, pretransplant serum parathyroid hormone level, and pretransplant calcium level [DPC] score; 0-15 points) to predict tertiary hyperparathyroidism. The median DPC score was higher in participants with post-transplant parathyroidectomy than in those without (13 versus three in derivation; 13 versus four in external validation; P<0.001 for all). Pretransplant dialysis duration, pretransplant serum parathyroid hormone level, and pretransplant calcium level score predicted post-transplant parathyroidectomy with comparable performance with the best-performing machine learning model in the test set (area under the receiver operating characteristic curve: 0.94 versus 0.92; area under the precision-recall curve: 0.52 versus 0.47). Serial measurement of DPC scores (≥13 at least two or more times, 3-month interval) during 12 months prior to kidney transplantation improved risk classification for post-transplant parathyroidectomy compared with single-time measurement (net reclassification improvement, 0.28; 95% confidence interval, 0.02 to 0.54; P=0.03).

CONCLUSIONS

A simple integer-based score predicted the risk of tertiary hyperparathyroidism in kidney allograft recipients, with improved classification by serial measurement compared with single-time measurement.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Korean Cohort Study for Outcome in Patients with Kidney Transplantation (KNOW-KT), NCT02042963 PODCAST: This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_06_10_CJN15921221.mp3.

Impact of parathyroidectomy on kidney graft function in post-transplant tertiary hyperparathyroidism: a comparative study

PURPOSE

Parathyroidectomy to treat tertiary hyperparathyroidism (THPT) is now on a par with calcimimetic treatment. The effects of cinacalcet and parathyroidectomy on kidney transplant function remain controversial. The aim of this study was to evaluate kidney transplant function in THPT patients treated either by parathyroidectomy, cinacalcet, or not treated.

METHODS

Between 2009 and 2019, 231 patients with functional grafts presenting THPT, defined either by calcaemia superior to 2.5 mmol/L with elevated PTH level or hypercalcaemia with non-adapted PTH level 1 year after kidney transplantation, were included. Hyperparathyroid patients treated by cinacalcet and parathyroidectomy were matched for age, sex, graft rank, and baseline eGFR with cinacalcet-only and untreated patients. Conditional logistic regression models were used to compare eGFR variations 1 year after parathyroidectomy between operated patients and matched controls. Five-year survivals were compared with the Mantel-Cox test.

RESULTS

Eleven patients treated with parathyroidectomy and cinacalcet were matched with 16 patients treated by cinacalcet-only and 29 untreated patients. Demographic characteristics were comparable between groups. Estimated odds ratios for eGFR evolution in operated patients compared with cinacalcet-only and untreated patients were 0.92 [95%CI 0.83-1.02] and 0.99 [0.89-1.10] respectively, indicating no significant impairment of eGFR 1 year after surgery. Five-year allograft survival was not significantly impaired in operated patients.

CONCLUSIONS

Parathyroidectomy did not appear to substantially alter or improve graft function 1 year after surgery or 5-year allograft survival. It could be hypothesized that in addition to its known benefits, parathyroidectomy can be safely performed vis-à-vis graft function in tertiary hyperparathyroidism.

Surgery is Underutilized in the Management of Tertiary Hyperparathyroidism

INTRODUCTION

Tertiary hyperparathyroidism (3HPT) is observed in up to 40% of renal transplant patients. Standard guidelines defining 3HPT and indications for operative intervention are not well described.

METHODS

We conducted a retrospective, single-institution cohort study of patients who underwent renal transplant between January 1, 2012 and January 30, 2018, with a minimum of 13-month follow-up and at least 1 y of allograft function. We defined 3HPT as having elevated serum level parathyroid hormone (>88 pg/mL) after successful renal transplantation or multiple instances of elevated serum calcium starting at least 3 mo after transplant. We compared graft failure rates after stratifying the cohort based on management strategy: expectant, medical management with cinacalcet, and parathyroidectomy.

RESULTS

Out of the 381 transplanted patients with functional grafts at 1 y, 178 patients (46.6%) were found to have 3HPT. One hundred twenty-nine patients (72.5%) were managed expectantly without medications, 35 patients (19.7%) were managed medically, and 14 patients (7.8%) were managed with parathyroidectomy. Twenty-two patients (17.1%) in the observation group had graft failure, 4 patients (11.4%) in the medically managed group had graft failure, and 0 patients in the surgery group had graft failure. Surgical intervention was associated with decreased renal allograft failure when compared to the combined cohort of nonoperative 3HPT patients (P = 0.03). All patients who underwent parathyroidectomy were cured and did not have graft failure as of December 30, 2019. Calcium elevation, but not PTH elevation, was associated with referral for parathyroidectomy on multivariable logistic regression analysis (P < 0.01).

CONCLUSIONS

At our institution, the referral rate for parathyroidectomy among patients with 3HPT remains low. Parathyroidectomy was associated with high cure rates and reduced graft failure. Surgery may be underutilized in the management of 3HPT.