Normalized Serum Calcium and Maintained Tacrolimus Levels by Cinacalcet Use in Kidney Transplant Recipients

Hypercalcemia with persistent hyperparathyroidism after kidney transplantation is an important risk of cardiovascular disease and allograft dysfunction in kidney transplant recipients (KTRs). Cinacalcet, a calcium-sensing receptor agonist, is commonly used in chronic hemodialysis recipients with secondary hyperparathyroidism; however, its effect and safety in kidney transplant recipients are not established.

A prospective cohort study was conducted in KTRs with persistent hyperparathyroidism (intact parathyroid hormone [iPTH] >65 pg/mL) for at least 1 year post-transplantation. Participants received cinacalcet 25 mg/day for 3 months. Primary outcomes were changes in serum calcium, serum phosphate, and iPTH concentrations; the secondary outcome was the effect on tacrolimus trough level.

Thirty KTRs (mean age, 46.5 years; median time since transplantation, 3 years; mean serum creatinine, 1.5 ± 0.4 mg/dL, mean estimated glomerular filtration rate, 55.4 ± 14.6 mL/min/1.73 m²) completed the study. Administration of cinacalcet significantly reduced serum calcium levels (mean, 9.2 ± 0.7 mg/dL vs 10.1 ± 0.6 mg/dL; P < .001) and increased serum phosphate levels (mean, 3.0 ± 0.6 mg/dL vs 2.7 ± 0.5 mg/dL; P = .006). iPTH levels showed no significant change (median, 178.3 pg/mL vs 176.2 pg/mL; P = .35). Tacrolimus trough levels remained stable (mean, 5.7 ± 1.3 vs 5.9 ± 2.8 ng/mL; P = .68).

Cinacalcet use can normalize serum calcium levels and maintain tacrolimus levels in KTRs with persistent hyperparathyroidism. However, long-term data, especially for cardiovascular outcomes, merit further exploration.