Introduction: persistent hypercalcemic secondary hyperparathyroidism (PSHPT) in kidney transplantation (KTx) can expose renal transplant recipients (RTRs) to a series of complications. Cinacalcet has been shown to be effective in controlling hypercalcemic PSHPT. Therefore, we evaluated the efficacy and tolerability of cinacalcet, over a period of 3 years, in the treatment of hypercalcemic PSHPT in a group of RTRs.
Patients and Methods: eight patients with a kidney transplant age > 12 months, parathyroid hormone (PTH) levels > 120 pg/ml and total serum calcium (TCa) levels > 10.5 mg/dl, were treated with cinacalcet at an initial dose of 30 mg/day. Hypercalcemic PSHPT picture must have been present for at least 6 months before the start of treatment with cinacalcet. Every 6-8 weeks were determined: estimated glomerular filtration rate (eGFR), PTH, TCa, serum phosphorus, fractional excretion of calcium (FECa), tubular maximum reabsorption rate of phosphate (TmP/GFR), serum tacrolimus. Annually all patients underwent to ultrasound control of the transplanted kidney. The main endpoints of the study were the reduction of PTH levels > 30% from baseline and the normalization of TCa levels (<10.2 mg/dl).
Results: the results are shown as median ± interquartile range (IQR). At follow-up PTH levels decreased from 223 (202-440) to 135 pg/ml (82-156) (P < 0.01), with a percentage decrease of -54 (-68;-44), TCa levels decreased from 11.0 (10.7-11.7) to 9.3 mg/dl (8.8-9.5) (P < 0.001). Serum phosphorus levels increased from 2.7 (2.0-3.0) to 3.2 mg/dl (2.9-3.5) (P < 0.05). Fractional excretion of calcium did not change, while TmPO4/GFR increased even not significantly. Renal function and serum levels of tacrolimus did not change throughout the observation period. At end of the study the average cinacalcet dosages were 30 mg/day (30-30). Ultrasound scans of the transplanted kidney showed no development of nephrocalcinosis and/or nephrolithiasis. Conclusions: cinacalcet has proved effective and well tolerated in the treatment of hypercalcemic PSHPT in RTRs.
Keywords: cinacalcet, hypercalcemia, persistent hypercalcemic secondary hyperparathyroidism, renal transplant.