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

BACKGROUND: Hyperparathyroidism persists in many patients after kidney transplantation. The purpose of this study was to evaluate the association between post-transplant hyperparathyroidism and kidney transplantation outcomes. METHODS: We identified 824 participants from a prospective longitudinal cohort of adult patients who underwent kidney transplantation at a single institution between December 2008 and February 2020. Parathyroid hormone levels before and after kidney transplantation were abstracted from medical records. Post-transplant hyperparathyroidism was defined as parathyroid hormone level ≥70 pg/mL 1 year after kidney transplantation. Cox proportional hazards models were used to estimate the adjusted hazard ratios of mortality and death-censored graft loss by post-transplant hyperparathyroidism. Models were adjusted for age, sex, race/ethnicity, college education, parathyroid hormone level before kidney transplantation, cause of kidney failure, and years on dialysis before kidney transplantation. A Wald test for interactions was used to evaluate the risk of death-censored graft loss by age, sex, and race. RESULTS: Of 824 recipients, 60.9% had post-transplant hyperparathyroidism. Compared with non-hyperparathyroidism patients, those with post-transplant hyperparathyroidism were more likely to be Black (47.2% vs 32.6%), undergo dialysis before kidney transplantation (86.9% vs 76.6%), and have a parathyroid hormone level ≥300 pg/mL before kidney transplantation (26.8% vs 9.5%) (all P < .001). Patients with post-transplant hyperparathyroidism had a 1.6-fold higher risk of death-censored graft loss (adjusted hazard ratio = 1.60, 95% confidence interval: 1.02–2.49) compared with those without post-transplant hyperparathyroidism. This risk more than doubled in those with parathyroid hormone ≥300 pg/mL 1 year after kidney transplantation (adjusted hazard ratio = 4.19, 95% confidence interval: 1.95–9.03). The risk of death-censored graft loss did not differ by age, sex, or race (all P(interaction) > .05). There was no association between post-transplant hyperparathyroidism and mortality. CONCLUSION: The risk of graft loss was significantly higher among patients with post-transplant hyperparathyroidism when compared with patients without post-transplant hyperparathyroidism.