Tertiary Hyperparathyroidism in Kidney Transplant Recipients

Abstract

Several treatment options exist for kidney transplant patients with tertiary hyperparathyroidism. However, the decision to endorse observation (OBS), medical therapy, or parathyroidectomy (PTX) remains controversial. We performed a retrospective cohort study of kidney transplant patients with tertiary hyperparathyroidism at a single institution over a 7-year period. Patients were classified by treatment mode: OBS, medical therapy with cinacalcet (CIN), or PTX. Descriptive statistics were performed. Serum calcium levels and change in serum creatinine level were compared using analysis of variance with comparisons between individual groups using the Student's t test with a Bonferroni correction. Time to treatment was compared between CIN and PTX groups using the Student's t test. Complication rates were compared using the Fisher exact test. We identified 83 patients: 52 were treated by OBS; 13 were treated with CIN, and 18 underwent PTX. Six weeks after treatment, PTX resulted in lower serum calcium level (9.28 mg/dL) compared with CIN (10.20 mg/dL) (P<0.01). There was no difference in the change in serum creatinine level 1 year after treatment initiation (P=0.98). Time to treatment was shorter (1.7 vs. 3.3 years, P<0.01), and the highest pretreatment calcium level was higher (12.2 vs. 11.7 mg/dL, P<0.01) in patients treated with PTX compared with CIN. Complication rates differed by treatment group (P<0.01). A quarter of OBS patients showed persistent hypercalcemic symptoms, compared with only 7.7% in the CIN group and 0% in the PTX group (P<0.01). PTX led to a greater reduction in serum calcium level and lower chance of persistent hypercalcemic symptoms, without any appreciable harm to the kidney allograft.