Clinical impact of hypercalcemia in kidney transplant

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.

Comparing subtotal parathyroidectomy and total parathyroidectomy with autotransplantation in renal transplant recipients

Background

Both subtotal parathyroidectomy (SPTX) and total parathyroidectomy with autotransplantation (TPTX + AT) are considered acceptable surgical approaches for renal patients. It is common that parathyroid surgery is performed in patients before they undergo kidney transplantation and there is currently no evidence considering the best surgical approach in this subset of patients.

Methods

Two cohorts were identified of consecutive patients who underwent parathyroidectomy for renal hyperparathyroidism by two surgeons at a single institution over equivalent time periods (SPTX and TPTX + AT). A retrospective chart review was performed to assess these techniques, including outcomes following kidney transplantation.

Results

There were 125 patients analysed, with 56 patients who underwent SPTX and 69 who underwent TPTX + AT. Both cohorts effectively reduced PTH post operatively. There were 22 patients in the SPTX cohort and 26 in the TPTX + AT cohort that subsequently received kidney transplants. There were no cases of recurrent hyperparathyroidism and one of hypoparathyroidism (4.5%) in the SPTX patients post-transplant. There was one case of recurrent hyperparathyroidism (3.8%) and four of persistent hypoparathyroidism (15.4%) in the TPTX + AT patients post-transplant.

Conclusions

Surgery for renal hyperparathyroidism requires a careful balance of the extent of parathyroid resection to prevent persistent/recurrent disease and avoid permanent hypoparathyroidism. SPTX may be a more appropriate option in kidney transplant candidates in order to minimise the risk of long-term hypoparathyroidism.

OSTEOPROTEGERIN AS AN EARLY SIGN OF CHRONIC KIDNEY DISEASE-MINERAL AND BONE DISORDER

Chronic kidney disease (CKD) is among the most significant health problems, with the associated cardiovascular disease and bone metabolism disorders being the leading cause of morbidity and mortality in these patients. The aim of the study was to determine markers of bone turnover in patient sera (phosphates, calcium, alkaline phosphatase, parathyroid hormone and osteoprotegerin (OPG)) in all stages of kidney failure including kidney transplant recipients. We also wanted to determine whether dialysis vintage affects recovery of bone markers one year after transplantation. There were 164 study patients, whereas 30 healthy individuals served as a control group. Serum OPG progressively increased with decline of the glomerular filtration rate. The highest OPG concentration was recorded in dialysis group. We observed a statistically significant OPG increase in stage 2 CKD. In kidney transplant group, there was positive correlation between OPG and dialysis vintage. We also found that serum OPG was lower in patients treated with dialysis for less than 4 years prior to transplantation. We confirmed that CKD-mineral and bone disorder began in stage 3 CKD with parathyroid hormone and OPG elevation, and a statistically significant OPG increase in stage 2 CKD might be an early sign of CKD-mineral and bone disorder. Dialysis vintage longer than 4 years is associated with more significant disturbances in mineral and bone metabolism.

Hyperparathyroidism at 1 year after kidney transplantation is associated with graft loss

BACKGROUND

Hyperparathyroidism persists in many patients after kidney transplantation. The purpose of this study was to evaluate the association between post-transplant hyperparathyroidism and kidney transplantation outcomes.

METHODS

We identified 824 participants from a prospective longitudinal cohort of adult patients who underwent kidney transplantation at a single institution between December 2008 and February 2020. Parathyroid hormone levels before and after kidney transplantation were abstracted from medical records. Post-transplant hyperparathyroidism was defined as parathyroid hormone level ≥70 pg/mL 1 year after kidney transplantation. Cox proportional hazards models were used to estimate the adjusted hazard ratios of mortality and death-censored graft loss by post-transplant hyperparathyroidism. Models were adjusted for age, sex, race/ethnicity, college education, parathyroid hormone level before kidney transplantation, cause of kidney failure, and years on dialysis before kidney transplantation. A Wald test for interactions was used to evaluate the risk of death-censored graft loss by age, sex, and race.

RESULTS

Of 824 recipients, 60.9% had post-transplant hyperparathyroidism. Compared with non-hyperparathyroidism patients, those with post-transplant hyperparathyroidism were more likely to be Black (47.2% vs 32.6%), undergo dialysis before kidney transplantation (86.9% vs 76.6%), and have a parathyroid hormone level ≥300 pg/mL before kidney transplantation (26.8% vs 9.5%) (all P < .001). Patients with post-transplant hyperparathyroidism had a 1.6-fold higher risk of death-censored graft loss (adjusted hazard ratio = 1.60, 95% confidence interval: 1.02-2.49) compared with those without post-transplant hyperparathyroidism. This risk more than doubled in those with parathyroid hormone ≥300 pg/mL 1 year after kidney transplantation (adjusted hazard ratio = 4.19, 95% confidence interval: 1.95-9.03). The risk of death-censored graft loss did not differ by age, sex, or race (all Pinteraction > .05). There was no association between post-transplant hyperparathyroidism and mortality.

CONCLUSION

The risk of graft loss was significantly higher among patients with post-transplant hyperparathyroidism when compared with patients without 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.

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.

Vitamin D and subclinical cardiac damage in a cohort of kidney transplanted patients: a retrospective observational study

In 178-kidney transplanted patients (KTxp), the prevalence of hypovitaminosis-D, the presence and novel development of left ventricular hypertrophy(LVH) and the correlations between native Vitamin-D (25OHD) and LVH were evaluated during the 1st year of transplantation (KTx). Clinical and instrumental data were recorded at pre-KTx and at one (T1) and 12 (T12) months after KTx. 25OHD levels were considered sufficient (s25OHD, ≥ 30 ng/dL) or insufficient (i25OHD, < 30 ng/dL). 25OHD correlated at T1 with parathormone(PTH), and at T12 with 25OHD-T1 and PTH-(T1,T12). At T12, s25OHD (15%) had higher 25OH and alkaline phosphatase (ALP), lower Ca, at T1, and lower PTH-(T1, T12) than i25OH-T12. At T1, KTxp with LVH (LVH-T1pos, 42%) were older and with longer dialysis vintage than LVH-T1neg. At T12, KTxp with LVH (LVH-T12pos, 53%) were older, with higher systolic blood pressure (SBP) at T12 than LVH-T12neg. No relation between 25OHD and LVH were found. Novel LVH was found in 14% of KTxp. They were older, had higher SBP-T12 and lower serum albumin-T12 than the others. LVH-modifications and 25OHD were not correlated. Hypovitaminosis-D is highly prevalent in KTxp. LVH correlates with different risk factors according to the time elapsed from KTx. However, during the 1st year of KTx, no relationship between LVH and 25OHD was observed.

Canadian Society of Nephrology Commentary on the Kidney Disease Improving Global Outcomes 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder

Purpose of review:

(1) To provide commentary on the 2017 update to the Kidney Disease Improving Global Outcomes (KDIGO) 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD); (2) to apply the evidence-based guideline update for implementation within the Canadian health care system; (3) to provide comment on the care of children with chronic kidney disease (CKD); and (4) to identify research priorities for Canadian patients.

Sources of information:

The KDIGO 2017 Clinical Practice Guideline Update for the Diagnosis, Evaluation, Prevention, and Treatment of CKD-MBD.

Methods:

The commentary committee co-chairs selected potential members based on their knowledge of the Canadian kidney community, aiming for wide representation from relevant disciplines, academic and community centers, and different geographical regions.

Key findings:

We agreed with many of the recommendations in the clinical practice guideline on the diagnosis, evaluation, prevention, and treatment of CKD-MBD. However, based on the uncommon occurrence of abnormalities in calcium and phosphate and the low likelihood of severe abnormalities in parathyroid hormone (PTH), we recommend against screening and monitoring levels of calcium, phosphate, PTH, and alkaline phosphatase in adults with CKD G3. We suggest and recommend monitoring these parameters in adults with CKD G4 and G5, respectively. In children, we agree that monitoring for CKD-MBD should begin in CKD G2, but we suggest measuring ionized calcium, rather than total calcium or calcium adjusted for albumin. With regard to vitamin D, we suggest against routine screening for vitamin D deficiency in adults with CKD G3-G5 and G1T-G5T and suggest following population health recommendations for adequate vitamin D intake. We recommend that the measurement and management of bone mineral density (BMD) be according to general population guidelines in CKD G3 and G3T, but we suggest against routine BMD testing in CKD G4-G5, CKD G4T-5T, and in children with CKD. Based on insufficient data, we also recommend against routine bone biopsy in clinical practice for adults with CKD or CKD-T, or in children with CKD, although we consider it an important research tool.

Limitations:

The committee relied on the evidence summaries produced by KDIGO. The CSN committee did not replicate or update the systematic reviews.

Type of subtotal parathyroidectomy and evolution of parathyroid hormone levels in end-stage renal disease patients: a retrospective cohort study

PURPOSE

Parathyroidectomy (PTX) is performed in end-stage renal disease (ESRD) for the treatment of secondary hyperparathyroidism. Whether and how the number of glands removed affects parathyroid hormone (PTH) levels remain controversial. The objective of this study is to compare the biochemical and pharmacological evolution after subtotal PTX according to the number of glands removed in ESRD.

METHODS

This is a unicenter longitudinal retrospective cohort study of ESRD patients who have undergone PTX [< 3 glands (group 1) vs ≥ 3 glands (group 2)] from April 2006 to October 2014 at CHU de Québec, Canada. Demographic data, comorbidities, pharmacological and biochemical parameters were collected before, 3, 6, 12 and 24 months after PTX. Linear mixed model was performed to compare the biochemical and pharmacological evolution.

RESULTS

We included 37 (13 in group 1, 24 in group 2) ESRD patients with a median age of 53 (46-58) years. The population is 68% male with a median dialysis vintage of 30.7 (18.0-61.2) months. The two groups were similar in terms of demographics and comorbidities. Compared to baseline, PTH levels in groups 1 and 2 dropped significantly at 2 years (1239-361 ng/L and 1542-398 ng/L, p < 0.05) but the evolution was comparable between the two groups.

CONCLUSIONS

Our results show the efficacy of subtotal PTX in lowering PTH levels in our ESRD cohort. However, the results were not different according to the number of glands removed.

US-guided microwave ablation for secondary hyperparathyroidism in patients after renal transplantation: a pilot study

OBJECTIVE

To assess the safety and efficacy of ultrasound-guided microwave ablation (MWA) in the treatment of patients who develop secondary hyperparathyroidism (SHPT) after renal transplantation (RT).

METHODS

In total, nine patients, each with symptomatic SHPT caused by RT and at least one enlarged parathyroid gland, underwent MWA via hydrodissection. Intact parathyroid hormone (i-PTH), serum calcium, serum phosphorus, creatinine and blood urea nitrogen concentrations, before and after MWA, were assessed and compared.

RESULTS

Complete ablation was achieved in all patients for a total of 14 ablated parathyroid glands. The mean follow-up time was 17.2 ± 1.7 months post-operation. The mean maximum diameter of the parathyroid glands was 1.3 ± 0.4 cm (range: 0.4-2.0 cm). The ablation power implemented was 30 W and the mean time for each parathyroid gland to achieve complete ablation was 287.5 ± 83.4 s. The mean i-PTH, serum calcium and phosphorus concentrations at one day post-MWA (69.6 pg/mL, 2.23 ± 0.29 mmol/L, 1.2 2 ± 0.48 mmol/L, respectively) were significantly lower than those before MWA (780.0 pg/mL, 2.62 ± 0.32 mmol/L, 1.39 ± 0.61 mmol/L, respectively; p < .01), whereas the creatinine and blood urea nitrogen concentrations before and after MWA did not differ significantly from each other (p > .05). No significant differences were found between the biomarker concentrations observed at one day post-MWA and at the follow-ups (p > .05). No major operation-related complications occurred.

CONCLUSION

Ultrasound-guided MWA is a safe and effective technique for destroying parathyroid gland tissue in patients who develop SHPT after RT and its clinical effects are long-lasting.

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.

Prevalence and predictors of early hypercalcemia after kidney transplantation: a nested case-control study within a cohort of 100 patients

BACKGROUND

Hypercalcemia (HC) after kidney transplantation (KTx) can deteriorate both graft and patient survival. However, HC as a clinical condition and its clinical significance after KTx remain unknown. We evaluated the prevalence and risk factors of early HC after KTx.

METHODS

We performed a nested case-control study using a cohort of 100 KTx patients. KTx patients were divided into the HC and normocalcemia (NC) groups based on the baseline serum-corrected calcium (cCa) levels (≥ 10.5 and < 10.5 mg/dL) within 1 year after KTx.

RESULTS

Overall, the median value of maximum serum cCa level within 1 year after KTx was 10.1 (9.1-13.8) mg/dL. Of the 100 KTx patients within the cohort, 31 patients (31.0%) were classified as the HC group. The maximum serum cCa level was reached significantly earlier in the HC group compared with the NC group (2 vs. 4 months, p = 0.024). In univariate analysis, the risk factors of early HC after KTx were dialysis duration ≥ 10 years, serum cCa level the day before KTx, and cinacalcet administration before KTx. Among these risk factors, serum cCa level the day before KTx and cinacalcet administration before KTx were identified as significant independent risk factors of early HC after KTx in multivariate analysis.

CONCLUSIONS

One-third of the KTx patients presented early HC within 1 year after KTx. Early HC after KTx resulted from persistent hyperparathyroidism. Therapeutic strategies to manage HC after KTx must be established.

Persistent hyperparathyroidism as a risk factor for long-term graft failure: the need to discuss indication for parathyroidectomy

BACKGROUND

Although a successful kidney transplant (KTx) improves most of the mineral and bone disorders (MBD) produced by chronic kidney disease (CKD), hyperparathyroidism may persist (pHPT). Current guidelines recommend parathyroidectomy if serum parathormone is persistently elevated 1 year after KTx, because pHPT has been recently associated with poor graft outcomes. However, whether patients with pHPT and adequate renal function are at risk for long-term graft failure is unknown.

METHODS

Longitudinal follow-up of 911 adults submitted to KTx between January 2005 and December 2014, with estimated glomerular filtration rate (eGFR) ≥ 30 mL/min 1 year after surgery. Clinical and laboratory data were collected from electronic database. Graft failure was defined as return to dialysis.

RESULTS

Overall, 62% of the patients were classified as having pHPT 1 year after KTx. After a mean follow-up time of 47 months, there were 59 graft failures (49 in pHPT and 10 in non-pHPT group, P = .003). At last follow-up, death-censored graft survival was lower in the pHPT group (P = .009), even after adjustment for age at KTx, donor age, donor type, acute rejection, parathyroidectomy, and eGFR at 1 year after transplantation (odds ratio [OR] 1.99; 1.004-3.971; P = .049). A PTH of 150 pg/mL at 6 months was the best cutoff to predict pHPT at 1 year (specificity = 92.1%).

CONCLUSION

Having pHPT after a successful KTx increases the long-term risk of death-censored graft failure. This result highlights the need for better recognition and management of CKD-MBD before and during the first year after KTx, and opens a discussion on the more appropriate timing to perform parathyroidectomy.

Nutritional Vitamin D in Renal Transplant Patients: Speculations and Reality

Reduced levels of nutritional vitamin D are commonly observed in most chronic kidney disease (CKD) patients and particularly in patients who have received a kidney transplant (KTx). In the complex clinical scenario characterizing the recipients of a renal graft, nutritional vitamin D deficiency has been put in relation not only to the changes of mineral and bone metabolism (MBM) after KTx, but also to most of the medical complications which burden KTx patients. In fact, referring to its alleged pleiotropic (non-MBM related) activities, vitamin D has been claimed to play some role in the occurrence of cardiovascular, metabolic, immunologic, neoplastic and infectious complications commonly observed in KTx recipients. Furthermore, low nutritional vitamin D levels have also been connected with graft dysfunction occurrence and progression. In this review, we will discuss the purported and the demonstrated effects of native vitamin D deficiency/insufficiency in most of the above mentioned fields, dealing separately with the MBM-related and the pleiotropic effects.

Cinacalcet versus Parathyroidectomy in the Treatment of Secondary Hyperparathyroidism Post Renal Transplantation

BACKGROUND

Persistent hyperparathyroidism (HPT) with hypercalcemia is prevalent after transplant and is considered a risk factor for progressive bone loss and fractures and vascular calcification, as well as the development of tubulointerstitial calcifications of renal allografts and graft dysfunction. The subtotal parathyroidectomy is the standard treatment, although currently it has been replaced by the calcimimetic cinacalcet.

AIM

The hypothesis of this study is that subtotal parathyroidectomy is superior to cinacalcet for treatment of persistent secondary parathyroidectomy post renal transplant, with minimal morbidity and significantly it reduces the cost of treatment after transplantation.

METHODS

We report our long-term clinical experience with either cinacalcet or parathyroidectomy in 59 kidney transplant recipients with hyperparathyroidism. Group one included medical treatment with cinacalcet and had 45 patients while parathyroidectomy patients (group 2) were 16 patients with two of them excluded because of surgical failure.

RESULTS

No difference was found between groups for any parameter. A greater short-term change of calcium and phosphorus homeostasis obtained by surgery than by cinacalcet, and in long term change, no significant difference between the two groups.

CONCLUSIONS

The main findings of this study are that correction of severe hyperparathyroidism was similar in both surgical and cinacalcet groups with the absence of a difference of long-term serum iPTH 1-84 levels between the two groups.

Prevalence of Hypercalcaemia in a Renal Transplant Population: A Single Centre Study

Introduction. Postrenal transplant bone disease is a significant problem. Factors influencing postrenal transplant bone status include high dose acute and low dose long-term steroid use, persistent hypercalcaemia, and graft failure. In this study, we aimed to determine the prevalence of hypercalcaemia and to evaluate the risk factors for postrenal transplant hypercalcaemia in long-term renal transplant patients at our centre. Methods. This is a biochemical audit in which we studied renal transplant recipients from the Central Northern Adelaide Renal Transplant Services, South Australia. Inclusion criteria include kidney transplant patients with functioning graft since 1971 and at least 3 months after transplantation at the time of analysis. Hypercalcaemia was defined as persistently elevated serum corrected calcium greater than or equal to 2.56 mmol/L for three consecutive months. Results. 679 renal transplant recipients with a functioning graft were studied and 101 were hypercalcaemic between March 2011 and June 2011 (15%). 60% of the hypercalcaemic patients were male and 40% were female, with chronic glomerulonephritis (39%) being the commonest cause of their end stage kidney disease (ESKD). Prevalence was similar in those that had haemodialysis and peritoneal dialysis pretransplantation. Hypercalcaemia in the renal transplant population was not secondary to suboptimal allograft function but secondary to pretransplantation hyperparathyroidism with persistent high parathyroid hormone (PTH) levels after transplantation. Conclusion. There is a high prevalence of hypercalcaemia (15%) in renal transplant recipients. The predominant cause for hypercalcaemia is pretransplantation hyperparathyroidism. The magnitude of pretransplantation hyperparathyroidism is the major determinant for long-term parathyroid function rather than graft function or pretransplantation duration on dialysis or mode of dialysis.

Hypercalcemia. Pathophysiological Aspects

The metabolic pathways that contribute to maintain serum calcium concentration in narrow physiological range include the bone remodeling process, intestinal absorption and renal tubule resorption. Dysbalance in these regulations may lead to hyper- or hypocalcemia. Hypercalcemia is a potentionally life-threatening and relatively common clinical problem, which is mostly associated with hyperparathyroidism and/or malignant diseases (90 %). Scarce causes of hypercalcemia involve renal failure, kidney transplantation, endocrinopathies, granulomatous diseases, and the long-term treatment with some pharmaceuticals (vitamin D, retinoic acid, lithium). Genetic causes of hypercalcemia involve familial hypocalciuric hypercalcemia associated with an inactivation mutation in the calcium sensing receptor gene and/or a mutation in the CYP24A1 gene. Furthermore, hypercalcemia accompanying primary hyperparathyroidism, which develops as part of multiple endocrine neoplasia (MEN1 and MEN2), is also genetically determined. In this review mechanisms of hypercalcemia are discussed. The objective of this article is a review of hypercalcemia obtained from a Medline bibliographic search.

Surgical management of secondary hyperparathyroidism in chronic kidney disease--a consensus report of the European Society of Endocrine Surgeons

BACKGROUND

Despite advances in the medical management of secondary hyperparathyroidism due to chronic renal failure and dialysis (renal hyperparathyroidism), parathyroid surgery remains an important treatment option in the spectrum of the disease. Patients with severe and complicated renal hyperparathyroidism (HPT), refractory or intolerant to medical therapy and patients with specific requirements in prospect of or excluded from renal transplantation may require parathyroidectomy for renal hyperparathyroidism.

METHODS

Present standard and actual controversial issues regarding surgical treatment of patients with hyperparathyroidism due to chronic renal failure were identified, and pertinent literature was searched and reviewed. Whenever applicable, evaluation of the level of evidence concerning diagnosis and management of renal hyperparathyroidism according to standard criteria and recommendation grading were employed. Results were discussed at the 6th Workshop of the European Society of Endocrine Surgeons entitled Hyperparathyroidism due to multiple gland disease: An evidence-based perspective.

RESULTS

Presently, literature reveals scant data, especially, no prospective randomized studies to provide sufficient levels of evidence to substantiate recommendations for surgery in renal hyperparathyroidism. Appropriate surgical management of renal hyperparathyroidism involves standard bilateral exploration with bilateral cervical thymectomy and a spectrum of four standardized types of parathyroid resection that reveal comparable outcome results with regard to levels of evidence and recommendation. Specific patient requirements may favour one over the other procedure according to individualized demands.

CONCLUSIONS

Surgery for patients with renal hyperparathyroidism in the era of calcimimetics continues to play an important role in selected patients and achieves efficient control of hyperparathyroidism. The overall success rate and long-term control of renal hyperparathyroidism and optimal handling of postoperative metabolic effects also depend on the timely indication, individually suitable type of parathyroid resection and specialized endocrine surgery.

Increased risk of all-cause mortality and renal graft loss in stable renal transplant recipients with hyperparathyroidism

BACKGROUND

Hyperparathyroidism is reported in 10% to 66% of renal transplant recipients (RTR). The influence of persisting hyperparathyroidism on long-term clinical outcomes in RTR has not been examined in a large prospective study.

METHODS

We investigated the association between baseline parathyroid hormone (PTH) levels and major cardiovascular events, renal graft loss, and all-cause mortality by Cox Proportional Hazard survival analyses in 1840 stable RTR derived from the Assessment of LEscol in Renal Transplantation trial. Patients were recruited in a mean of 5.1 years after transplantation, and follow-up time was 6 to 7 years.

RESULTS

Significant associations between PTH and all 3 outcomes were found in univariate analyses. When adjusting for a range of plausible confounders, including measures of renal function and serum mineral levels, PTH remained significantly associated with all-cause mortality (4% increased risk per 10 units; P=0.004), and with graft loss (6% increased risk per 10 units; P<0.001), but not with major cardiovascular events. Parathyroid hormone above the upper limit of normal (65 pg/mL) indicated a 46% (P=0.006) higher risk of death and an 85% higher risk of graft loss (P<0.001) compared with low/normal values.

CONCLUSIONS

Hyperparathyroidism is an independent, potentially remediable, risk factor for renal graft loss and all-cause mortality in RTR.

Changes in bone mineral metabolism parameters, including FGF23, after discontinuing cinacalcet at kidney transplantation

Little is known about the effects of the administration of cinacalcet in dialytic patients who are scheduled for kidney transplantation, and in particular about the changes in FGF23 and other mineral metabolism parameters after surgery compared with recipients not on cinacalcet at kidney transplantation. We performed a prospective observational cohort study with recruitment of consecutive kidney transplant recipients at our institution. Patients were classified according to whether they were under treatment with cinacalcet before transplantation. Bone mineral metabolism parameters, including C-terminal FGF23, were measured at baseline, on day 15, and at 1, 3, and 6 months after transplantation. In previously cinacalcet-treated patients, cinacalcet therapy was discontinued on the day of surgery and was not restarted after transplantation. A total of 48 kidney transplant recipients, 20 on cinacalcet at surgery and 28 cinacalcet non-treated patients, completed the follow-up. Serum phosphate declined significantly in the first 15 days after transplantation with no differences between the two groups, whereas cinacalcet-treated patients showed higher FGF23 levels, although not significant. After transplantation, PTH and serum calcium were significantly higher in cinacalcet-treated patients. We conclude that patients receiving cinacalcet on dialysis presented similar serum phosphate levels but higher PTH and serum calcium levels during the initial six months after kidney transplantation than cinacalcet non-treated patients. The group previously treated with cinacalcet before transplantation showed higher FGF23 levels without significant differences, so further studies should investigate its relevance in the management of these patients.

Long-term clinical practice experience with cinacalcet for treatment of hypercalcemic hyperparathyroidism after kidney transplantation

Within this prospective, open-label, self-controlled study, we evaluated the long-term effects of the calcimimetic cinacalcet on calcium and phosphate homeostasis in 44 kidney transplant recipients (KTRs) with hypercalcemic hyperparathyroidism by comparing biochemical parameters of mineral metabolism between pre- and posttreatment periods. Results are described as mean differences (95% CIs) between pre- and posttreatment medians that summarize all repeated measurements of a parameter of interest between the date of initial hypercalcemia and cinacalcet initiation (median of 1.6 (IQR: 0.6-3.8) years) and up to four years after treatment start, respectively. Cinacalcet was initiated after 1.8 (0.8-4.7) years posttransplant and maintained for 6.2 (3.9-7.6) years. It significantly decreased total serum calcium (-0.30 (-0.34 to -0.26) mmol/L, P < 0.001) and parathyroid hormone levels (-79 (-103 to -55) pg/mL, P < 0.001). Serum levels of inorganic phosphate (Pi) and renal tubular reabsorption of phosphate to glomerular filtration rate (TmP/GFR) increased simultaneously (Pi: 0.19 (0.15-0.23) mmol/L, P < 0.001, TmP/GFR: 0.20 (0.16-0.23) mmol/L, P < 0.001). In summary, cinacalcet effectively controlled hypercalcemic hyperparathyroidism in KTRs in the long-term and increased low Pi levels without causing hyperphosphatemia, pointing towards a novel indication for the use of cinacalcet in KTRs.

Pneumocystis jirovecii pneumonia with an atypical granulomatous response after kidney transplantation

Pneumocystis jirovecii pneumonia (PCP) continues to be a leading cause of morbidity and mortality in kidney transplant recipients. Granulomatous PCP is an unusual histological presentation that has been described in a variety of immunosuppressive conditions. Previous studies have demonstrated an association between granulomatous disorders and hypercalcemia, the purported mechanism of which is extrarenal production of 1,25-dihydroxyvitamin D by activated macrophages. Here, we report a case of granulomatous formation in a kidney transplant recipient with PCP who presented with hypercalcemia and suppressed parathyroid hormone, both of which resolved after successful treatment of the pneumonia. In immunocompromised patients, pulmonary infection associated with hypercalcemia should raise the suspicion of PCP and other granulomatous disorders.