Therapeutic management of post-kidney transplant hyperparathyroidism

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.

Fibroblast growth factor 23-Klotho and mineral metabolism in the first year after pediatric kidney transplantation: A single-center prospective study

BACKGROUND

The role of fibroblast growth factor 23 (FGF23) levels in mineral metabolism before and after kidney transplantation in pediatric patients is poorly understood.

METHODS

We prospectively evaluated 24 patients under 18 years of age (4.5 [3.3-9.8] years) who underwent living kidney transplantation between July 2016 and March 2018, and measured intact FGF23 and serum αKlotho levels, and other parameters of mineral metabolism before and after transplantation (Day 7, 1 and 4 months, and 1 year). Relationships between parameters were examined by linear analysis.

RESULTS

FGF23 level was 440.8 [63.4-5916.3] pg/ml pre-transplant and decreased significantly to 37.1 [16.0-71.5] pg/ml at Day 7 post-transplant (-91.6%, p < .001). Thereafter, it remained at normal levels until 1 year. αKlotho level was 785 [568-1292] pg/ml pre-transplant and remained low at Day 7 and 1 month post-transplant, with an increasing trend at 4 months. Post-transplant phosphorus levels were significantly decreased compared with pre-transplant, with a lowest level of 1.7 [1.3-2.9] mg/dl, -5.7 [-6.8, -3.8] SD at Day 4, followed by gradual recovery. Phosphorus levels and the ratio of tubular maximum phosphate reabsorption were significantly and negatively associated with pre-transplant FGF23 until 4 months of post-transplant. Pre-transplant αKlotho was negatively associated with pre-transplant FGF23 but not FGF23 or other parameters after transplantation.

CONCLUSION

FGF23 in pediatric kidney transplant patients decreased rapidly after transplantation and associated with post-transplant hypophosphatemia and increased phosphorus excretion. Post-transplant αKlotho was low early post-transplant but tended to increase subsequently. Post-transplant αKlotho was unaffected by pre-transplant FGF23 or other factors, suggesting pre-transplant chronic kidney disease status has no effect.

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.

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.

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.

Association Between Treatment of Secondary Hyperparathyroidism and Posttransplant Outcomes

BACKGROUND

Secondary hyperparathyroidism (SHPT) affects nearly all patients on maintenance dialysis therapy. SHPT treatment options have considerably evolved over the past 2 decades but vary in degree of improvement in SHPT. Therefore, we hypothesize that the risks of adverse outcomes after kidney transplantation (KT) may differ by SHPT treatment.

METHODS

Using the Scientific Registry of Transplant Recipients and Medicare claims data, we identified 5094 adults (age ≥18 y) treated with cinacalcet or parathyroidectomy for SHPT before receiving KT between 2007 and 2016. We quantified the association between SHPT treatment and delayed graft function and acute rejection using adjusted logistic models and tertiary hyperparathyroidism (THPT), graft failure, and death using adjusted Cox proportional hazards; we tested whether these associations differed by patient characteristics.

RESULTS

Of 5094 KT recipients who were treated for SHPT while on dialysis, 228 (4.5%) underwent parathyroidectomy, and 4866 (95.5%) received cinacalcet. There was no association between treatment of SHPT and posttransplant delayed graft function, graft failure, or death. However, compared with patients treated with cinacalcet, those treated with parathyroidectomy had a lower risk of developing THPT (adjusted hazard ratio, 0.56; 95% confidence interval, 0.35-0.89) post-KT. Furthermore, this risk differed by dialysis vintage (Pinteraction = 0.039). Among patients on maintenance dialysis therapy for ≥3 y before KT (n = 3477, 68.3%), the risk of developing THPT was lower when treated with parathyroidectomy (adjusted hazard ratio, 0.43; 95% confidence interval, 0.24-0.79).

CONCLUSIONS

Parathyroidectomy should be considered as treatment for SHPT, especially in KT candidates on maintenance dialysis for ≥3 y. Additionally, patients treated with cinacalcet for SHPT should undergo close surveillance for development of tertiary hyperparathyroidism post-KT.

Outcomes of Subtotal Parathyroidectomy Versus Total Parathyroidectomy With Autotransplantation for Tertiary Hyperparathyroidism: Multi-institutional Study

OBJECTIVES

Due to the paucity of data and controversy regarding the preferred surgical approach for managing tertiary HPT, we sought to investigate the outcomes of different surgical approaches in managing this challenging disease.

METHODS

We performed a multi-center retrospective study to include patients with tertiary HPT who underwent STPX or total parathyroidectomy with autotransplantation (TPX-A).

RESULTS

One hundred five patients had kidney transplant, and 43 were on dialysis. In the kidney transplant group, 61 patients underwent STPX, and 44 for TPX-A. Patients' demographics were not significantly different (48.61 ± 9.31 vs 47.95 ± 12.73 years, P = 0.759. The postoperative follow-up showed that the TPX-A cohort had a higher rate of hypoparathyroidism (N = 20, 45.45%) versus (N = 14, 22.95%) with the STPX cohort (P = 0.013). The cure among the TPX-A cohorts (84.09%) over the STPX cohort (73.77%) (P = 0.153). The long-term follow-up showed that the rate of developing temporary (N = 16, 41.03%) or permanent (N = 8, 20.51%) hypoparathyroidism was significantly higher among patients who underwent TPX-A over the patients who underwent STPX (N = 7, 17.95%), and (N = 4, 10.26%), respectively (P = 0.012). There was no statistical difference between the persistence (N = 3, 7.69%) or the recurrence (N = 2, 5.13%) of the HPT in the TPX-A cohort and the STPX cohort (N = 2, 5.13%). (N = 4, 10.26%), respectively, P = 0.644.

CONCLUSIONS

To our knowledge, this is the largest multi-center study that compared different approaches for managing tertiary HPT. Showing that STPX is the better modality in patients diagnosed with tertiary HPT and had kidney transplants avoiding the risk of hypoparathyroidism.

Therapy for persistent hypercalcemic hyperparathyroidism post-renal transplant: cinacalcet versus parathyroidectomy

Background:

Persistent hyperparathyroidism post-transplant is associated with increases in the incidence of cardiovascular events, fractures, and deaths. The aim of this study was to compare both therapeutic options available: parathyroidectomy (PTX) and the calcimimetic agent cinacalcet.

Methods:

A single center retrospective study including adult renal transplant recipients who developed hypercalcemia due to persistent hyperparathyroidism. Inclusion criteria: PTH > 65 pg/mL with serum calcium > 11.5 mg/dL at any time after transplant or serum calcium persistently higher than 10.2 mg/dL one year after transplant. Patients treated with cinacalcet (n=46) were compared to patients treated with parathyroidectomy (n=30). Follow-up period was one year. Clinical and laboratory data were analyzed to compare efficacy and safety of both therapeutic modalities.

Results:

PTX controlled calcemia faster (month 1 x month 6) and reached significantly lower levels at month 12 (9.1±1.2 vs 9.7±0.8 mg/dL, p < 0.05); PTX patients showed significantly higher levels of serum phosphate (3.8±1.0 vs 2.9±0.5 mg/dL, p < 0.05) and returned PTH to normal levels (45±51 pg/mL). Cinacalcet, despite controlling calcium and phosphate in the long term, decreased but did not correct PTH (197±97 pg/mL). The proportion of patients that remained with PTH above normal range was 95% in the cinacalcet group and 22% in the PTX group. Patients treated with cinacalcet had better renal function (creatinine 1.2±0.3 vs 1.7±0.7 mg/dL, p < 0.05).

Conclusions:

Surgical treatment was superior to cinacalcet to correct the metabolic disorders of hyperparathyroidism despite being associated with worse renal function in the long term. Cinacalcet proved to be a safe and well tolerated drug.

Influence of Pretransplant Factors on Posttransplant Anemia Recovery Rate in Primary Deceased Donor Kidney Transplant Recipients

OBJECTIVES

Our objective was to evaluate the influence of pretransplant risk factors on posttransplant anemia recovery.

MATERIALS AND METHODS

This single-center observational retrospective study included 80 deceased donor kidney transplant recipients who had been followed up to 16 months after kidney transplant. Time point of posttransplant anemia recovery was considered the time when hemoglobin of 11.0 g/dL was achieved and maintained for 3 consecutive monthly visits. We collected donor/transplant characteristics (age, sex, hypertension history, cause of death, donor kidney function, expanded criteria donor status, deceased donor score, HLA mismatch, and cold ischemia time) and recipient data (pretransplant hemoglobin, parathyroid hormone, kidney graft function, delayed graft function, acute rejection, infections, surgical bleeding, posttransplant parathyroid hormone, iron stores, and C-reactive protein and tacrolimus levels). We used univariate and multivariate Cox proportional hazards analyses and Kaplan-Meier plots to determine associations between variables and posttransplant anemia recovery rate. P < .05 was considered significant.

RESULTS

We identified 62 deceased donors (33 male; mean age 50 ± 15.1 years) and 80 kidney transplant recipients (52 male; mean age 47.0 ± 10.6 years). Mean pretransplant hemoglobin was 11.4 ± 1.5 g/dL. Donor age, deceased donor score, pretransplant parathyroid hormone, posttransplant transferrin saturation (all P < .05), and tacrolimus level (P < .01) were significantly related to posttransplant anemia recovery. Kaplan-Meier curve identified that recipients of deceased donors below 60 years old achieved hemoglobin of 11.0 g/dL more frequently and earlier than recipients of deceased donors above 60 years old (P < .05).

CONCLUSIONS

Deceased donor age, deceased donor score, pretransplant serum parathyroid hormone, posttransplant transferrin saturation, and tacrolimus level were significantly associated with posttransplant anemia recovery rate in deceased donor kidney transplant recipients. Anemia recovery was more frequent and earlier in recipients of deceased donors below 60 years than in recipients of donors 60 years old and above.

Influence of Parathyroidectomy on Kidney Graft Function in Secondary and Tertiary Hyperparathyroidism

BACKGROUND

Timing of parathyroidectomy (PTX) remains controversial in candidates for kidney transplant with concomitant renal hyperparathyroidism (HPT). The aim of this retrospective study was to identify the influence of early vs late posttransplant PTX compared to pretransplant PTX on renal graft function and morbidity.

METHODS

This single-center cohort study includes 57 patients with renal HPT and kidney transplantation treated between 2007 and 2017. Ninety-six patients had surgery for renal HPT between 2007 and 2017 as a consecutive sample. Group 1 (n = 30; tertiary HPT), group 2 (n = 66; secondary HPT). Of group 1, 4 patients were excluded for PTX before and after kidney transplantation. In group 2, 20 patients were excluded since they had not undergone kidney transplantation during follow-up. Twelve patients were excluded because of short follow-up (kidney transplantation in 2018), and 3 patients were excluded because of transplant failure within 90 days. Twenty-six patients underwent posttransplant PTX (10 patients within 12 months after transplant), and 31 patients had undergone PTX prior to kidney transplantation. Graft function, serum calcium concentrations, parathyroid hormone (PTH) levels, postoperative morbidity, and 90-day mortality were recorded.

RESULTS

Median age was 53.1 years in group 1 and 49.1 years in group 2. Most patients were male (53.8% in group 1; 54.8% in group 2). Median preoperative PTH levels were significantly different with 331.6 pg/mL in group 1 and 667.5 pg/mL in group 2 (P = .003). Creatinine levels changed little from 1.4 mg/dL (range, 0.8-2.5) to 1.7 mg/dL (range, 0.7-7.3) in group 1, and no difference was seen between early or late PTX after transplantation. In group 2, creatinine levels were 8.5 mg/dL (range, 4.6-11.7) before PTX and 8.7 mg/dL (range, 5.1-11.9) after PTX. We saw no correlation between postoperative PTH and kidney function. Thirty-five patients with postoperative PTH < 15 pg/mL displayed a mean postoperative creatinine of 5.5 mg/dL (range, 4.3-6.8), similar to other patients. Both the 30-day and 90-day mortality rates were zero.

CONCLUSIONS

PTX had no negative effect on graft function, whether performed before or after (early or late) kidney transplantation. Surgical cure of renal HPT should be performed as soon as possible to prevent secondary complications and can also be safely carried out early after transplantation.

Behavior of Calcium, Phosphorus, and Parathormone Before Transplantation and in Months 1, 3, 6, 9, and 12 After Transplantation

BACKGROUND

Bone mineral disease after transplantation persists and is an issue that must be addressed owing to the cardiovascular impact it presents. The objective of this study is to present the behavior of calcium, phosphorus, and parathormone (PTH) before renal transplantation (RT) and throughout the 12 months after transplant surgery.

METHODS

A longitudinal observational study of RT patients was performed from 2013 to 2017 in 2 renal transplant units in Mexico. In total, 1009 records of patients with RT were analyzed. Calcium, phosphorus, and PTH levels were studied before transplantation and for 12 months after. Central tendency and dispersion were measured, the difference of means was established with chi square or student t tests, and the significant value of P was set at <.05. We also used the SPSS statistical package, version 25.

RESULTS

Phosphorus had a median pre-RT of 5.73, which decreased to 2.8 in the first month post-transplant and then increased to 3.41 at 12 months post-RT. The median PTH, on the other hand, started at 420.60 and decreased to 67.45. Calcium began at 9.04 and hit a plateau of 9.58 during month 12 after the surgical event.

CONCLUSIONS

Of the 3 biochemical parameters evaluated, phosphorus was the one that most corrected itself after transplantation. Despite a tendency toward hypophosphatemia in the first month after transplantation, it began to normalize from month 6 on. Meanwhile, calcium was the biochemical value that changed the least after transplantation.

Long-term renal graft outcome after parathyroidectomy - a retrospective single centre study

BACKGROUND

Surgical correction of hyperparathyroidism after kidney transplantation has been associated with significant graft function decline. We examined the effects of parathyroidectomy on short- and long-term graft function and its potential predictors.

METHODS

For this retrospective, monocentric study we identified 48 (5.5%) out of 892 patients from our protocol biopsy program who received renal transplantation between 2000 and 2007, with parathyroidectomy after transplantation. Data from up to three years after parathyroidectomy was collected and analyzed with multivariable linear regression analyses.

RESULTS

Main indications for parathyroidectomy were hypercalcemia and graft calcifications. Parathyroidectomy was successful in 47 patients, with a median drop in serum intact parathormone (iPTH) from 394 to 21 pg/ml. Mean estimated glomerular fitration rate (eGFR) before parathyroidectomy was 60 ± 26 ml/min. At three months after parathyroidectomy, the eGFR was 46 ± 18 ml/min (p < 0.001) but remained stable at one and three years (50 ± 20; 49 ± 20 ml/min). The median annual eGFR change was - 0.5 ml/min before and + 1.0 ml/min after parathyroidectomy. Multivariable modeling identified high iPTH levels and higher eGFR before parathyroidectomy as predictors of the eGFR drop after parathyroidectomy. Lower graft function twelve months after parathyroidectomy was predicted by the eGFR before and the iPTH drop after surgery.

CONCLUSIONS

These results indicate that the extent of parathyroidectomy is critical and too much lowering of iPTH should be avoided by timely parathyroidectomy, before reaching extreme high iPTH values. In view of the observed loss of eGFR, parathyroidectomy can be considered safe in patients with an eGFR above 30 ml/min.

Biochemical Characteristics of Bone Mineral Metabolism before and throughout the First Year after Kidney Transplantation, Persistent Hyperparathyroidism, and Risk Factors in a Latin Population

Bone mineral metabolism disease, which included persistent hyperparathyroidism, is common after successful kidney transplantation (KT) and is related with negative outcomes in kidney transplant recipients. There is a lack of information about bone mineral metabolism, persistent hyperparathyroidism, and its risk factors in Latin kidney transplant recipients (KTRs). Material and Methods: A retrospective study was conducted in 74 patients aged 18-50 years with evolution of 12 months after KT and estimated glomerular filtration rate (eGFR) >60 ml/min; biochemical data of bone mineral metabolism before and at 1, 3, 6, and 12 months of KT were registered. Results. Age was 33 (IQR 27-37) years; 54% (n = 40) were men. Before KT, all patients had hyperparathyroidism, 40% (n = 30) hypocalcemia, 86% (n = 64) hyperphosphatemia, and 42% (n = 31) hyperphosphatasemia. After KT, an increase of calcium and a diminution of PTH, phosphorus, and alkaline phosphatase were corroborated (p=0.001). All patients had hypovitaminosis D (deficiency: 91% (n = 67); insufficiency: 9% (n = 7)); 40% (n = 30) had persistent hyperparathyroidism at 12 months. Hyperphosphatasemia before KT (OR = 4.17 (95% CI: 1.21-14.44); p=0.04), hyperparathyroidism at 6 months (OR = 1.84 (95% CI; 1.67-2.06); p=0.02), hypovitaminosis D at 6 months (OR = 3.94 (95% CI: 1.86-17.9); p=0.01), and hyperphosphatasemia at 6 months (OR = 1.47 (95% CI: 1.07-2.86); p=0.03) were risk factors for persistent hyperparathyroidism at 12 months after KT. Conclusion. Persistent hyperparathyroidism at 6 months, hypovitaminosis D, and hyperphosphatasemia are risk factors for persistent hyperparathyroidism at 1 year of KT in Latin population.

Management of Post-transplant Hyperparathyroidism and Bone Disease

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

Parathyroidectomy versus cinacalcet for tertiary hyperparathyroidism; a retrospective analysis

Introduction

Tertiary hyperparathyroidism (tHPT), i.e., persistent HPT after kidney transplantation, affects 17–50% of transplant recipients. Treatment of tHPT is mandatory since persistently elevated PTH concentrations after KTx increase the risk of renal allograft dysfunction and osteoporosis. The introduction of cinacalcet in 2004 seemed to offer a medical treatment alternative to parathyroidectomy (PTx). However, the optimal management of tHPT remains unclear.

Methods

A retrospective analysis was performed on patients receiving a kidney transplantation (KT) in two academic centers in the Netherlands. Thirty patients undergoing PTx within 3 years of transplantation and 64 patients treated with cinacalcet 1 year after transplantation for tHPT were included. Primary outcomes were serum calcium and PTH concentrations 1 year after KT and after PTx.

Results

Serum calcium normalized in both the cinacalcet and the PTx patients. PTH concentrations remained above the upper limit of normal (median 22.0 pmol/L) 1 year after KT, but returned to within the normal range in the PTx group (median 3.7 pmol/L). Side effects of cinacalcet were difficult to assess; minor complications occurred in three patients. Re-exploration due to persistent tHPT was performed in three (10%) patients.

Conclusion

In patients with tHPT, cinacalcet normalizes serum calcium, but does not lead to a normalization of serum PTH concentrations. In contrast, PTx leads to a normalization of both serum calcium and PTH concentrations. These findings suggest that PTx is the treatment of choice for tHPT.

Maintenance low dose systemic glucocorticoids have limited impact on bone strength and mineral density among incident renal allograft recipients: A pilot prospective cohort study

Soon after kidney transplant (KT), a decrease in parathormone and bone mineral density (BMD) occur, but little is known on the impact of KT on novel bone quality parameters including trabecular bone score (TBS) and bone material strength index (BMSi). We aimed to study BMD, TBS and BMSi in the first year after KT, in patients not treated with any bone therapy. A cohort including 36 patients underwent KT on a low-glucocorticoid-dose protocol (5 mg daily-prednisone from post-operative-day 42 onwards) and was observed for 12 months prospectively. At 3 months, phosphorus and parathormone decreased, while calcium increased. We also observed at 3 months a transient mild 2.9% bone loss at femoral neck (BMD change 0.752 ± 0.15 vs 0.730 ± 0.15; p = 0.004), but no change at either spine or total hip. Both TBS and BMSi remained stable. At 12 months, lumbar (but not total hip or femoral neck) BMD slightly decreased by 2.1% vs baseline (0.950 ± 0.15 vs 0.930 ± 0.5; p = 0.046), while TBS and BMSi remained unmodified. In KT patients on low-dose glucocorticoids and no bone therapy, there were small BMD decreases at femoral neck (at 3 months) and lumbar spine (at 12 months), but no change in either TBS or BMSi. Low-dose post-KT glucocorticoid treatment shows limited impact on bone, supporting steroid-restrictive protocols.

Management of mineral and bone disorders in renal transplant recipients

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

Advances in the evaluation of bone health in kidney transplant patients

Bone disease related to chronic kidney disease and, particularly, to kidney transplant patients is a common cause or morbidity and mortality, especially due to a higher risk of osteoporotic fractures. Despite the fact that this has been known for decades, to date, an appropriate diagnostic strategy has yet to be established. Apart from bone biopsy, which is invasive and scarcely used, no other technique is available to accurately establish the risk of fracture in kidney patients. Techniques applied to the general population, such as bone densitometry, have not been subjected to sufficient external validation and their use is not systematic. This means that the identification of patients at risk of fracture and therefore those who are candidates for preventive strategies is an unmet need. Bone strength, defined as the ability of the bone to resist fracture, is determined by bone mineral density (measured by bone densitometry), trabecular architecture and bone tissue quality. The trabecular bone score estimates bone microarchitecture, and low values have been described as an independent predictor of increased fracture risk. Bone microindentation is a minimally invasive technique that measures resistance of the bone to micro-cracks (microscopic separation of mineralised collagen fibres), and therefore bone tissue biomechanical properties. The superiority over bone densitometry of the correlation between the parameters measured by trabecular bone score and microindentation with the risk of fracture in diverse populations led us to test its feasibility in chronic kidney disease and kidney transplant patients.

Bone density, microarchitecture, and material strength in chronic kidney disease patients at the time of kidney transplantation

Bone health is assessed by bone mineral density (BMD). Other techniques such as trabecular bone score and microindentation could improve the risk of fracture's estimation. Our chronic kidney disease (CKD) patients presented worse bone health (density, microarchitecture, mechanical properties) than controls. More than BMD should be done to evaluate patients at risk of fracture.

INTRODUCTION

BMD measured by dual-energy X-ray absorptiometry (DXA) is used to assess bone health in end-stage renal disease (ESRD) patients. Recently, trabecular bone score (TBS) and microindentation that can measure microarchitectural and mechanical properties of bone have demonstrated better correlation with fractures than DXA in different populations. We aimed to characterize bone health (BMD, TBS, and strength) and calcium/phosphate metabolism in a cohort of 53 ESRD patients undergoing kidney transplantation (KT) and 94 controls with normal renal function.

METHODS

Laboratory workout, lumbar spine/hip BMD measurements (using DXA), lumbar spine TBS, and bone strength were carried out. The latter was assessed with an impact microindentation device, standardized as percentage of a reference value, and expressed as bone material strength index (BMSi) units. Multivariable linear regression was used to study differences between cases and controls adjusted by age, gender, and body mass index.

RESULTS

Among cases, serum calcium was 9.6 ± 0.7 mg/dl, phosphorus 4.4 ± 1.2 mg/dl, and intact parathyroid hormone 214 pg/ml [102-390]. Fourteen patients (26.4%) had prevalent asymptomatic fractures in spinal X-ray. BMD was significantly lower among ESRD patients compared to controls: lumbar 0.966 ± 0.15 vs 0.982 ± 0.15 (adjusted p = 0.037), total hip 0.852 ± 0.15 vs 0.902 ± 0.13 (adjusted p < 0.001), and femoral neck 0.733 ± 0.15 vs 0.775 ± 0.12 (adjusted p < 0.001), as were TBS (1.20 [1.11-1.30] vs 1.31 [1.19-1.43] (adjusted p < 0.001)) and BMSi (79 [71.8-84.2] vs 82. [77.5-88.9] (adjusted p = 0.005)).

CONCLUSIONS

ESRD patients undergoing transplant surgery have damaged bone health parameters (density, microarchitecture, and mechanical properties) despite acceptably controlled hyperparathyroidism. Detecting these abnormalities may assist in identifying patients at high risk of post-transplantation fractures.

Systematic review of surgical and medical treatment for tertiary hyperparathyroidism

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Hypocalcemia immediately after renal transplantation

BACKGROUND

After renal transplantation (RTX), hypercalcemia, mainly due to persistent hyperparathyroidism, and hypophosphatemia, caused by the improved ability to excrete phosphorus in the renal tubules, are expected. However, immediately after RTX, a transient reduction in serum calcium (Ca) levels has been previously reported, the reason for which is not clear.

PATIENTS AND METHODS

In 21 patients receiving ABO compatible living donor kidney transplants, serum levels of Ca, phosphorus, intact parathyroid hormone (iPTH), 1,25-dihydroxyvitamin D, and tacrolimus were measured within three wk after RTX, along with urinary Ca and phosphorus excretion. The immunosuppressive regimen consisted of a three-drug combination including a glucocorticoid, a calcineurin inhibitor, and an antimetabolite agent.

RESULTS

Serum Ca levels declined significantly during the first post-operative week. Urinary Ca excretion increased immediately after RTX and gradually normalized. Increased urinary Ca excretion did not correlate with serum levels of iPTH and tacrolimus.

CONCLUSIONS

Immediately after RTX, regardless of serum iPTH and tacrolimus levels, transient increases in urinary Ca excretion and hypocalcemia were observed. Administration of glucocorticoids is one potential cause of inappropriate urinary Ca wasting.

Cinacalcet effect on polymorphonuclear leucocytes of kidney transplant patients

BACKGROUND

Polymorphonuclear leucocytes (PMNLs) play a key role in the nonspecific immune defence. Cinacalcet reduces serum calcium levels in kidney transplant recipients with mineral bone disorder associated with chronic kidney disease. We investigated essential functions of PMNLs of kidney transplant recipients with and without hypercalcaemia and with and without cinacalcet therapy.

SUBJECTS AND METHODS

Oxidative burst, phagocytosis, apoptosis and intracellular calcium concentrations of PMNLs from normocalcaemic kidney transplant patients without (KT-NC) or with cinacalcet intake (KT-NC/CI), hypercalcaemic kidney transplant patients (KT-HC) and healthy subjects (HS) were investigated.

RESULTS

Stimulation of oxidative burst of PMNLs from KT-HC patients by phorbol-12-myristate-13-acetate or Escherichia coli was significantly attenuated compared with PMNLs from KT-NC, KT-NC/CI and HS. Apoptosis of PMNLs from KT-HC patients was significantly decreased compared with cells from KT-NC, KT-NC/CI and HS. Apoptosis correlated significantly with serum calcium concentrations. Intracellular calcium concentrations and phagocytosis of PMNLs did not differ between groups.

CONCLUSIONS

Our data indicate that stimulation of PMNL oxidative burst and apoptosis is significantly diminished in kidney transplant patients with hypercalcaemia, while kidney transplant patients with serum calcium levels normalized by cinacalcet have normal PMNL functions despite immunosuppressive therapy.

Atypical presentation of a brown tumor in a kidney transplant recipient: a case report

Brown tumor is a rare complication of secondary hyperparathyroidism. It is exceptionally encountered after kidney transplantation. We here report on a 54-year-old male recipient who developed a brown tumor localized in the right forearm, and whose initial presentation was atypical, mimicking a bone tumor. Hence, diagnosis of brown tumors should be suggested by clinicians in a context of hyperparathyroidism.

CKD-mineral and bone disorder management in kidney transplant recipients

Kidney transplantation, the most effective treatment for the metabolic abnormalities of chronic kidney disease (CKD), only partially corrects CKD-mineral and bone disorders. Posttransplantation bone disease, one of the major complications of kidney transplantation, is characterized by accelerated loss of bone mineral density and increased risk of fractures and osteonecrosis. The pathogenesis of posttransplantation bone disease is multifactorial and includes the persistent manifestations of pretransplantation CKD-mineral and bone disorder, peritransplantation changes in the fibroblast growth factor 23-parathyroid hormone-vitamin D axis, metabolic perturbations such as persistent hypophosphatemia and hypercalcemia, and the effects of immunosuppressive therapies. Posttransplantation fractures occur more commonly at peripheral than central sites. Although there is significant loss of bone density after transplantation, the evidence linking posttransplantation bone loss and subsequent fracture risk is circumstantial. Presently, there are no prospective clinical trials that define the optimal therapy for posttransplantation bone disease. Combined pharmacologic therapy that targets multiple components of the disordered pathways has been used. Although bisphosphonate or calcitriol therapy can preserve bone mineral density after transplantation, there is no evidence that these agents decrease fracture risk. Moreover, bisphosphonates pose potential risks for adynamic bone disease.

Hyperparathyroidism in chronic kidney disease: complexities within the commonplace

Secondary hyperparathyroidism in patients with chronic kidney disease (CKD) is common and usually caused by associated metabolic abnormalities, in particular, hypocalcaemia and hyperphosphataemia. Nevertheless, other causes of hyperparathyroidism can exist concurrently with CKD, challenging diagnostic interpretation and therapeutic intervention. We present four cases of hyperparathyroidism in patients with CKD that highlight some of these dilemmas.

New options for the management of hyperparathyroidism after renal transplantation

The persistence and severity of hyperparathyroidism (HPT) post-renal transplantation is relatively frequent and primarily associated with the timing and its magnitude in the pre-transplant period and with the presence of parathyroid adenomas. HPT after renal transplantation is clinically manifested with hypercalcemia, hypophosphatemia, bone pain, fractures, and in more serious cases with cardiovascular calcifications that affect the survival. The primary clinical objective for patients with secondary HPT after renal transplantation is to obtain a level of parathyroid hormone (PTH) adequate to the renal transplanted function and to normalize levels of calcium, phosphorus and vitamin D. In many cases during this period, the development of hypercalcemia and/or hypophosphatemia makes it necessary to take different therapeutic measures. The use of vitamin D or its analogues has been extrapolated from the management of pre-transplant HPT obtaining variable outcomes, although its use is limited by its capacity to produce hypercalcemia. Calcimimetics are drugs that have proven be effective in reducing PTH levels in patients with HPT on dialysis and has been effective in reducing up to 50% PTH levels in moderate to severe HPT in post-renal transplantation.When HPT persists after renal transplantation and does not respond to medical treatment, invasive management by percutaneous ethanol injection therapy of parathyroid glands or parathyroidectomy should be considered. The emergence of new methods for the management of HPT expands the availability of therapeutic tools for transplant patients.

Tertiary hyperparathyroidism resistant to cinacalcet treatment

Cinacalcet hydrochloride (cinacalcet) has been reported to be efficacious for patients with tertiary hyperparathyroidism (THPT). We experienced five patients with THPT requiring parathyroidectomy (PTx) because of resistance to cinacalcet treatment and investigated their clinical characteristics and clinical course. The maximum diameter of the parathyroid gland estimated by ultrasonography before renal transplantation was evaluated. Serum total calcium, phosphorus, intact parathyroid hormone (iPTH), alkaline phosphatase (ALP), and creatinine (Cr) levels were investigated every three months after the administration of cinacalcet and at PTx. After surgery, the Cr levels were followed. In all five patients, at least one parathyroid gland had a largest diameter of more than 1 cm, and the mean diameter was 18.7 mm (range 14.9-24.1 mm). Intact PTH and ALP levels gradually increased after the initiation of cinacalcet and the Cr levels transiently increased after PTx. These findings suggest that the existence of a severely enlarged nodular hyperplastic gland is a main factor involved in resistance to cinacalcet.