Resolution of Secondary Hyperparathyroidism after Kidney Transplantation and the Effect on Graft Survival
Rongzhi Wang*, Griffin Price, Mitchell Disharoon, Gabe Stidham, Chandler McLeod, Jessica L. McMullin, Andrea Gillis, Jessica Fazendin, Brenessa Lindeman, Song Ong, Herbert Chen
University of Alabama at Birmingham, Birmingham, AL
Objective: Hyperparathyroidism (HPT) is nearly universal in patients with end-stage kidney disease. Kidney transplantation (KT) is thought to cure renal hyperparathyroidism in the majority of patients, but most studies have only focused on following calcium and not parathyroid hormone (PTH) levels. We sought to study the prevalence of persistent HPT after KT at our center and its effect on graft survival.
Methods: Patients who underwent KT from January 2015 to August 2021 were included and characterized by post-KT HPT status at the most recent follow-up: resolved (achieving normal PTH after KT) versus persistent HPT. Those with persistent HPT were further stratified by the occurrence of hypercalcemic episodes (normocalcemic versus hypercalcemic HPT group). Patient demographics, donor kidney quality, perioperative PTH and calcium levels, and allograft function were compared between groups. Multivariable logistic regression and cox regression with propensity score matching (PSM) were conducted.
Results: Of 1554 patients, only 333 (21.4%) patients had resolution of renal HPT after KT with a mean (±SD) follow-up length of 40 ± 23 months. The median (IQR) length of HPT resolution was 4 (0-14) months. Of the remaining 1196 patients with persistent HPT after KT, 863 (72.2%) patients had high PTH and normal calcium levels, while 358 (29.9%) patients had high calcium and high PTH levels. Patients with persistent HPT had higher PTH levels at the time of KT [402.6 (240.3 – 646.3) vs. 256.7 (153.4 – 441.2) pg/mL, p<0.001] and were more likely to receive cinacalcet treatment both before and after KT (33.7% and 20.1% vs. 12.9% and 6.6% respectively, p<0.001). Only 6.0% of patients with persistent HPT received parathyroidectomy. Multivariable logistic regression showed race, cinacalcet use before KT, dialysis before KT, deceased donor, high PTH, and calcium levels at KT were associated with persistent HPT after KT. After adjusting for patient demographics and donor kidney quality by PSM, persistent HPT (HR 2.4, 95% CI 1.1 – 5.4, p=0.029, figure 1) was associated with a higher risk of allograft failure. Sub-analysis showed that both hypercalcemic HPT (HR 2.7, 95% CI 1.1 – 6.8, p=0.032, figure 2) and normocalcemic HPT (HR 2.7, 95% CI 1.3-6.0, p=0.011, figure 3) were associated with increased risk of allograft failure when compared to patients with resolved HPT.
Conclusion: Persistent hyperparathyroidism is common (79%) after kidney transplantation, which is associated with a higher risk of allograft failure. PTH levels should be closely monitored after kidney transplantation so that patients with persistent HPT can be treated appropriately.
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