Characteristics of Persistent Hyperparathyroidism After Renal Transplantation

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.

Calcium phosphate deposition, tertiary hyperparathyroidism, and the long-term effect on kidney allografts

BACKGROUND

Tertiary hyperparathyroidism adversely affects kidney allografts, with calcium phosphate deposition hypothesized to be an underlying cause. We analyzed allograft biopsies to investigate risk factors for calcium phosphate deposition and understand its impact on allograft function.

METHODS

We reviewed patients who underwent kidney transplantation from 2017 to 2019. Tertiary hyperparathyroidism was defined as an elevated parathyroid hormone and hypercalcemia beyond 3 months' posttransplant or being prescribed cinacalcet. Allograft failure was defined as needing dialysis posttransplantation or retransplantation beyond 3 months' posttransplant. Three- and 12-month allograft biopsies were reviewed for calcium phosphate deposition. The χ2, t-test, and multivariate regression were used for statistical analysis.

RESULTS

Of 159 patients who underwent kidney transplantation, 59 (37.1%) were diagnosed with tertiary hyperparathyroidism. Longer preoperative dialysis vintage (odds ratio, 1.47; confidence interval, 1.22-1.80 P < .001) and preoperative cinacalcet usage (odds ratio, 18.4; confidence interval, 7.24-53.0 P < .001) were associated with tertiary hyperparathyroidism. In total, 36 of 59 (61%) patients with tertiary hyperparathyroidism had calcium phosphate deposition on 3- or 12-month kidney allograft biopsy compared with 23 of 100 (23%) patients without tertiary hyperparathyroidism (P < .001). Tertiary hyperparathyroidism (odds ratio, 6.01; confidence interval, 2.91-13.0 P < .001) was associated with calcium phosphate deposition. Calcium phosphate deposition and tertiary hyperparathyroidism were not associated with worse glomerular filtration rate at 3 years' posttransplantation. Of those with data available at 3 years' posttransplantation, 21 of 49 (42.9%) patients remained on cinacalcet. There were 3 of 159 (2%) patients who had allograft failure, 2 of whom had both tertiary hyperparathyroidism and calcium phosphate deposition.

CONCLUSION

Preoperative variables associated with tertiary hyperparathyroidism included longer dialysis vintage and cinacalcet use. Tertiary hyperparathyroidism was the main risk factor for calcium phosphate deposition posttransplantation. In our population, calcium phosphate deposition and tertiary hyperparathyroidism were not significantly associated with lower glomerular filtration rate.

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.

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.

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.

Persistent hyperparathyroidism after preemptive kidney transplantation

BACKGROUND

Long-term dialysis vintage is a predictor of persistent hyperparathyroidism (HPT) after kidney transplantation (KTx). Recently, preemptive kidney transplantation (PKT) has increased. However, the incidence, predictors, and clinical implications of HPT after PKT are unclear. Here, we aimed to elucidate these considerations.

METHODS

In this retrospective cohort study, we enrolled patients who underwent PKT between 2000 and 2016. Those who lost their graft within 1 year posttransplant were excluded. HPT was defined as an intact parathyroid hormone (PTH) level exceeding 80 pg/mL or hypercalcemia unexplained by causes other than HPT. Patients were divided into two groups based on the presence of HPT 1 year after PKT. The primary outcome was the predictors of HPT after PKT, and the secondary outcome was graft survival.

RESULTS

Among the 340 consecutive patients who underwent PKT, 188 did not have HPT (HPT-free group) and 152 had HPT (HPT group). Multivariate logistic regression analysis revealed that pretransplant PTH level (P < 0.001; odds ratio [OR], 5.480; 95% confidence interval [CI], 2.070-14.50) and preoperative donor-estimated glomerular filtration rate (P = 0.033; OR, 0.978; 95% CI, 0.957-0.998) were independent predictors of HPT after PKT. Death-censored graft survival was significantly lower in the HPT group than that in the HPT-free group (90.4% vs. 96.4% at 10 years, P = 0.009).

CONCLUSIONS

Pretransplant PTH levels and donor kidney function were independent predictors of HPT after PKT. In addition, HPT was associated with worse graft outcomes even after PKT.

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.

Timing of parathyroidectomy for kidney transplant patients with secondary hyperparathyroidism: A practical overview

Kidney transplantation remains the best treatment for patients with end-stage kidney disease, and it could partially mitigate systemic disorders of mineral and bone metabolism caused by secondary hyperparathyroidism. However, persistent hyperparathyroidism is still observed in 30-60% of patients 1 year after kidney transplantation, leading to impairment of allograft function and a disturbance of mineral metabolism. The timing of parathyroidectomy varies among transplant centers because the possible negative effects of parathyroidectomy on allograft outcomes are still unclear. This review provides a comprehensive and detailed overview of the natural course of hyperparathyroidism following kidney transplantation and the effects of the timing and extent of parathyroidectomy on allograft function. It aims to provide useful information for surgeons to propose an appropriate intervention strategy to break the vicious cycle of post-kidney transplantation hyperparathyroidism and deterioration of allograft function.

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.

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.

Clinical Prediction of High-Turnover Bone Disease After Kidney Transplantation

Bone histomorphometric analysis is the most accurate method for the evaluation of bone turnover, but non-invasive tools are also required. We studied whether bone biomarkers can predict high bone turnover determined by bone histomorphometry after kidney transplantation. We retrospectively evaluated the results of bone biopsy specimens obtained from kidney transplant recipients due to the clinical suspicion of high bone turnover between 2000 and 2015. Bone biomarkers were acquired concurrently. Of 813 kidney transplant recipients, 154 (19%) biopsies were taken at a median of 28 (interquartile range, 18-70) months after engraftment. Of 114 patients included in the statistical analysis, 80 (70%) presented with high bone turnover. Normal or low bone turnover was detected in 34 patients (30%). For discriminating high bone turnover from non-high, alkaline phosphatase, parathyroid hormone, and ionized calcium had the areas under the receiver operating characteristic curve (AUCs) of 0.704, 0.661, and 0.619, respectively. The combination of these markers performed better with an AUC of 0.775. The positive predictive value for high turnover at a predicted probability cutoff of 90% was 95% while the negative predictive value was 35%. This study concurs with previous observations that hyperparathyroidism with or without hypercalcemia does not necessarily imply high bone turnover in kidney transplant recipients. The prediction of high bone turnover can be improved by considering alkaline phosphatase levels, as presented in the logistic regression model. If bone biopsy is not readily available, this model may serve as clinically available tool in recognizing high turnover after engraftment.

Prevalence and risk factors for tertiary hyperparathyroidism in kidney transplant recipients

BACKGROUND

Tertiary hyperparathyroidism after kidney transplantation has been associated with graft dysfunction, cardiovascular morbidity, and osteopenia; however, its true prevalence is unclear. The objective of our study was to evaluate the prevalence of and risk factors for tertiary hyperparathyroidism.

METHODS

A prospective cohort of 849 adult kidney transplantation recipients (December 2008-February 2020) was used to estimate the prevalence of hyperparathyroidism 1-year post-kidney transplant. Tertiary hyperparathyroidism was defined as hypercalcemia (≥10mg/dL) and hyperparathyroidism (parathyroid hormone≥70pg/mL) 1-year post-kidney transplantation. Modified Poisson regression models were used to evaluate risk factors associated with the development of both persistent hyperparathyroidism and tertiary hyperparathyroidism.

RESULTS

Among kidney transplantation recipients, 524 (61.7%) had persistent hyperparathyroidism and 182 (21.5%) had tertiary hyperparathyroidism at 1-year post-kidney transplantation. Calcimimetic use before kidney transplantation was associated with 1.30-fold higher risk of persistent hyperparathyroidism (adjusted prevalence ratio = 1.30, 95% CI: 1.12-1.51) and 1.84-fold higher risk of tertiary hyperparathyroidism (adjusted prevalence ratio = 1.84, 95% CI: 1.25-2.72). Pre-kidney transplantation parathyroid hormone ≥300 pg/mL was associated with 1.49-fold higher risk of persistent hyperparathyroidism (adjusted prevalence ratio = 1.49, 95% CI = 1.19-1.85) and 2.21-fold higher risk of tertiary hyperparathyroidism (adjusted prevalence ratio = 2.21, 95% CI = 1.25-3.90). Pre-kidney transplantation tertiary hyperparathyroidism was associated with an increased risk of post-kidney transplantation tertiary hyperparathyroidism (adjusted prevalence ratio = 1.71, 95% CI = 1.29-2.27), but not persistent hyperparathyroidism. Furthermore, 73.0% of patients with persistent hyperparathyroidism and 61.5% with tertiary hyperparathyroidism did not receive any treatment at 1-year post-kidney transplantation.

CONCLUSION

Persistent hyperparathyroidism affected 61.7% and tertiary hyperparathyroidism affected 21.5% of kidney transplantation recipients; however, the majority of patients were not treated. Pre-kidney transplantation parathyroid hormone levels ≥300pg/mL and the use of calcimimetics are associated with the development of tertiary hyperparathyroidism. These findings encourage the re-evaluation of recommended pre-kidney transplantation parathyroid hormone thresholds and reconsideration of pre-kidney transplantation secondary hyperparathyroidism treatments to avoid the adverse sequelae of tertiary hyperparathyroidism in kidney transplantation recipients.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Effect of Pretransplant Use of Calcimimetic on Parathyroid Function after Renal Transplantation

OBJECTIVE

Persistence of hyperparathyroidism (HPT) after renal transplantation leads to undesirable outcomes such as increase in cardiovascular events, graft dysfunction, and increased mortality. Options for therapy include medical management with calcimimetic or operative management. The present study was undertaken to evaluate the natural history of HPT after renal transplantation and to determine risk factors for persistent HPT in the era of calcimimetic.

DESIGN

The study is a retrospective review of data from 74 consecutive patients who underwent renal transplantation at our institution from April 2011 to November 2019.

METHODS

The natural history of HPT after renal transplantation and associations between intact parathyroid hormone (PTH) level after transplantation and clinical variables such as age, sex, duration of pretransplant dialysis, and use of calcimimetic before transplantation were evaluated.

RESULTS

Intact PTH decreased after renal transplantation in most of the patients without receiving parathyroidectomy. Known risk factors of persistent HPT did not associate with intact PTH level after renal transplantation in patients who had been receiving calcimimetic before transplantation.

CONCLUSION

In conclusion, we have found that HPT after renal transplantation could be managed successfully by medical treatments. When predicting the prognosis of HPT after transplantation, pretransplant use of calcimimetic should be taken into consideration.

Comparison of Pre- and Post-transplant Parathyroidectomy in Renal Transplant Recipients and the Impact of Parathyroidectomy Timing on Calcium Metabolism and Renal Allograft Function: A Retrospective Single-Center Analysis

BACKGROUND

The effect of parathyroidectomy (PTx) timing on serum calcium (Ca) levels and renal functions in renal transplant recipients with severe hyperparathyroidism (HPT) remains unclear. We retrospectively aimed to investigate and compare the clinical data of patients who underwent pre- and post-transplant PTx and elucidated the impact of PTx timing on serum Ca levels and renal graft outcomes after renal transplantation (RTx).

METHODS

During January 2000-December 2016, 53 and 55 patients underwent post-transplant PTx (Post-RTx group) and pretransplant PTx (Pre-RTx group), respectively. The serum Ca levels and estimated glomerular filtration rate (eGFR) were assessed in both groups.

RESULTS

At the end of the follow-up, the serum Ca levels were significantly higher and the incidence of hypocalcemia was significantly lower in the Pre-RTx group than in the Post-RTx group [9.5 vs. 8.9 mg/dL, P < 0.001; 14.5% vs. 34.0%, P = 0.024]. The decrease in the eGFR 12-36 months after RTx was more significant in the Post-RTx group than in the Pre-RTx group (-13.8% vs. -0.9%; P = 0.001). A logistic regression involving age, sex, dialysis period, and serum parathormone level revealed that post-transplant PTx is an independent risk factor for persistent hypocalcemia at the end of the follow-up (P = 0.034) and for a >20% decrease in the eGFR 12-36 months after RTx (P = 0.029).

CONCLUSIONS

In renal transplant candidates with severe HPT, pretransplant PTx should be considered to prevent persistent hypocalcemia and deterioration of the renal graft function.

Parathyroidectomy for tertiary hyperparathyroidism after second kidney transplantation: a case report

Successful kidney transplantation usually resolves secondary hyperparathyroidism (SHPT). However, some patients fail to normalize, and their condition is often referred to as tertiary hyperparathyroidism (THPT). Surgical consensus on the timing of post-transplant parathyroidectomy (PTX) for THPT has not been reached. Herein, we report a case of a 58-year-old post-transplant woman, considering the concrete timing of PTX for both SHPT and THPT. She initiated hemodialysis with end-stage renal disease at the age of 24, and underwent first kidney transplantation at the age of 28. When peritoneal dialysis (PD) was induced due to the worsening kidney function at the age of 50, the serum intact parathyroid hormone (iPTH) level remarkably increased (2332 pg/mL). Although cinacalcet was administered, the patient's iPTH levels were not sufficiently suppressed for seven years. Diagnostic images including ultrasound, computed tomography, and ^99mTc-methoxyisobutylisonitrile scintigraphy indicated THPT as the reason for prolonged post-transplant hypercalcemia. Therefore, PTX was performed 14 months after the second transplantation. Histology showed nodular hyperplasia of all parathyroid glands, indicating autonomous secretion of parathyroid hormone. In general, patients with more severe THPT are recognized with more severe SHPT prior to transplantation during the dialysis period. We should consider a referral for surgery based on the individual risk factors. We recommend to perform parathyroidectomy earlier, before the kidney transplantation in the clinical suspicion of severe SHPT.

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.

Endocrine surgery during and after the COVID-19 epidemic: Expert guidelines from AFCE

The COVID-19 pandemic commands a major reorganisation of the entire French healthcare system. In France, general rules have been issued nationally and implemented by each healthcare centre, both public and private, throughout France. Guidelines drafted by an expert group led by the French-speaking Association of Endocrine Surgery (AFCE) propose specific surgical management principles for thyroid, parathyroid, endocrine pancreas and adrenal surgery during and after the COVID-19 epidemic.

[Endocrine surgery during and after the COVID-19 epidemic: Guidelines from AFCE]

La pandémie de COVID-19 impose une réorganisation majeure de l’ensemble de notre système de soins. En France, des règles générales ont été diffusées au niveau national et sont déclinées par chaque établissement, public comme privé, sur l’ensemble du territoire. Ces recommandations, rédigées par un groupe d’experts sous l’égide de l’Association francophone de chirurgie endocrinienne (AFCE), ont pour objectif de proposer des principes spécifiques de prise en charge chirurgicale au cours et au décours de l’épidémie de COVID- 19, pour les pathologies chirurgicales de la thyroïde, des parathyroïdes, du pancréas endocrine, et des surrénales.

Influence of Pre-renal Transplant Secondary Hyperparathyroidism on Later Evolution After Transplantation

Persistence of secondary hyperparathyroidism (SHPT) is common after renal transplantation. Good diagnosis and treatment are important to avoid complications. The objective of our work was to perform a retrospective analysis of the evolution of SHPT after renal transplantation. We selected patients who had received a kidney transplant at our hospital between 2000 and 2014. The biochemical variables of chronic kidney disease-metabolic bone disorders (CKD-MBD) were collected at pretransplantation and at 3, 6, 12, and 24 months post-transplantation. Treatments related to SHPT were also analyzed. Five hundred forty-three renal transplants were included. The average preoperative parathyroid hormone (PTH) was 241.14 pg/mL, 115.7 pg/mL at 3 months, and at 12 and 24 months postoperatively, PTH levels stabilized to 112 pg/mL. Treatment related to SHPT was present in 27.3% of patients during the preoperative period, 40.4% at 3 months postoperatively, 24.2% at 12 months postoperatively, and 23.2% at 24 months postoperatively. There was a significant association between requiring some type of treatment preoperatively and the rest of the postoperative periods (P < .005). The sample was later divided into 3 groups based on preoperative PTH (1: <150 pg/mL, n = 223 [41.1%]; 2: 150-300 pg/mL, n = 173 [31.9%]; 3: >300 pg/mL, n = 147 [27.1%]) and their evolutions were compared. Higher levels of postoperative PTH in group pre-PTH 3 were observed. Group 3 also presented with greater need for treatment in the postoperative periods, with significant association (P < .05). A regression analysis was performed and found that postoperative PTH were dependent on preoperative PTH adjusted by glomerular filtration. In conclusion, parameters related to CKD-MBD (mainly PTH) after kidney transplant, dependent on preoperative levels and glomerular filtration. Patients with a greater grade of SHPT presented with higher levels of postoperative PTH despite receiving more intensive treatment.

Parathyroidectomy versus Cinacalcet in the Management of Tertiary Hyperparathyroidism: Surgery Improves Renal Transplant Allograft Survival

BACKGROUND

Renal transplant allograft function in patients with tertiary hyperparathyroidism who are treated with cinacalcet versus parathyroidectomy remains unclear.

METHODS

This is a retrospective, single-center review of patients with tertiary hyperparathyroidism between 2000 and 2017. We compared clinical parameters and outcomes, including renal allograft failure in patients who had undergone parathyroidectomy versus treatment with cinacalcet therapy.

RESULTS

A total of 133 patients were included (33 who received parathyroidectomy and 100 who received cinacalcet); median renal allograft survival was 5.9 years (interquartile range 4.0-9.0). There were no differences in age, sex, body mass index, comorbidities, duration of pretransplant dialysis, cadaveric donor utilization, or rates of delayed allograft function between cohorts. In the parathyroidectomy cohort, normalization of parathyroid hormone occurred more frequently (67% vs 15%, P < .001) and renal allograft failure rates were less (9% vs 33%, P = .007), with similar median posttransplant follow-up (7.0 years [interquartile range 4.5-10.0]). On multivariable analysis, parathyroidectomy was inversely associated with allograft failure (odds ratio 0.20, 95%-confidence interval 0.06-0.71, P = .013); there were no other associated factors. A greater median parathyroid hormone (pg/mL) 1 year posttransplant (348 [interquartile range 204-493] vs 195 [interquartile range 147-297], P = .025) was associated with allograft failure in the cinacalcet cohort.

CONCLUSION

Parathyroidectomy for tertiary hyperparathyroidism is associated with lesser rates of renal allograft failure compared with cinacalcet management. Patients with inadequate parathyroid hormone control on cinacalcet at 1 year posttransplant should be considered for parathyroidectomy to prevent potential allograft failure.

Initial surgical results of 500 Parathyroidectomies for Hyperparathyroidism related to chronic kidney disease - mineral and bone disorder

Introduction:

Surgical treatment of hyperparathyroidism related to chronic kidney disease is a challenging procedure even for experienced parathyroid surgeons. Over the years, adjuvant techniques have been developed to assist the medical team to improve surgical outcomes. However, medical staff in poor countries have less access to these techniques and the effectiveness of surgery in this context is unclear.

Objective:

verify the effectiveness of surgery for treatment of hyperparathyroidism related to chronic kidney disease without adjuvant techniques.

Methods:

Over a 5-years period, patients with hyperparathyroidism that had clinical therapeutic failure were evaluated for surgical treatment. Total parathyroidectomy with autograft or subtotal resection were the selected procedures. Surgeries were performed in a tertiary hospital in Brazil without the assistance of some of the adjuvant techniques that are usually applied, such as frozen section, nerve monitoring, and gamma probe. Intraoperative PTH and localization pre-operative exams were applied, but with huge restrictions.

Results:

A total of 518 patients with hyperparathyroidism (128 secondary and 390 tertiary) were surgically treated. Total parathyroidectomy were performed in 81.5%, subtotal in 12.4%, and 61% of patients had a surgical failure. Of all failures, only 1.4% needed a second surgery totaling 98.6% of successful initial surgical treatment. Neck hematoma and unilateral focal fold paralysis occurred in 1.9% and 1.5%, respectively.

Conclusion:

parathyroidectomy is a safe and reproducible surgical procedure even in the absence of adjuvant techniques.

Risk factors for persistent hyperparathyroidism in children with stable renal function after kidney transplantation

This study aimed to investigate the risk factors for PHPT in children with stable renal function who received KT. We retrospectively analyzed the clinical findings and laboratory results of patients who underwent KT below 19 years of age, between 1996 and 2016 at our hospital. Patients were followed up for more than 1 year after KT. We calculated the mean ± standard deviation or median [minimum - maximum] for each parameter. We included a total of 46 patients (male:female = 26:20). Twelve patients (26.1%) were included in the PHPT group, and 34 (73.9%) were in the nPTH group. The dialysis duration was 57.1 ± 49.9, 44 [0-145] months in the PHPT group and 23.5 ± 25.8, 15 [1-121] months in the nPTH group (P = .040). The post-KT total CO2 level was significantly higher in the PHPT group (P = .022). The pre- (P = .021) and post-KT (P = .005) and 3-month average (P = .018) iPTH levels were also significantly higher in PHPT group. The height z-score showed a negative correlation, and the pre-KT, 3-month average phosphorus and alkaline phosphate levels showed positive correlations with iPTH levels, at 1 year after KT. Patients who undergo prolonged durations of dialysis, have increased iPTH levels before and after KT, and have low bicarbonate levels after KT are at risk of PHPT and should be monitored carefully.

Vitamin D-Mediated Hypercalcemia: Mechanisms, Diagnosis, and Treatment

Hypercalcemia occurs in up to 4% of the population in association with malignancy, primary hyperparathyroidism, ingestion of excessive calcium and/or vitamin D, ectopic production of 1,25-dihydroxyvitamin D [1,25(OH)₂D], and impaired degradation of 1,25(OH)₂D. The ingestion of excessive amounts of vitamin D₃ (or vitamin D₂) results in hypercalcemia and hypercalciuria due to the formation of supraphysiological amounts of 25-hydroxyvitamin D [25(OH)D] that bind to the vitamin D receptor, albeit with lower affinity than the active form of the vitamin, 1,25(OH)₂D, and the formation of 5,6-trans 25(OH)D, which binds to the vitamin D receptor more tightly than 25(OH)D. In patients with granulomatous disease such as sarcoidosis or tuberculosis and tumors such as lymphomas, hypercalcemia occurs as a result of the activity of ectopic 25(OH)D-1-hydroxylase (CYP27B1) expressed in macrophages or tumor cells and the formation of excessive amounts of 1,25(OH)₂D. Recent work has identified a novel cause of non-PTH-mediated hypercalcemia that occurs when the degradation of 1,25(OH)₂D is impaired as a result of mutations of the 1,25(OH)₂D-24-hydroxylase cytochrome P450 (CYP24A1). Patients with biallelic and, in some instances, monoallelic mutations of the CYP24A1 gene have elevated serum calcium concentrations associated with elevated serum 1,25(OH)₂D, suppressed PTH concentrations, hypercalciuria, nephrocalcinosis, nephrolithiasis, and on occasion, reduced bone density. Of interest, first-time calcium renal stone formers have elevated 1,25(OH)₂D and evidence of impaired 24-hydroxylase-mediated 1,25(OH)₂D degradation. We will describe the biochemical processes associated with the synthesis and degradation of various vitamin D metabolites, the clinical features of the vitamin D-mediated hypercalcemia, their biochemical diagnosis, and treatment.