Background: Persistent hyperparathyroidism (HPT) is observed in approximately 50% of kidney transplant recipients one year after transplantation. It may result in hypercalcemia, hypophosphatemia, bone demineralization, vascular calcification, lithiasis, and participate in chronic allograft nephropathy. We evaluated the use of the calcimimetic cinacalcet chloride to correct chronic hypercalcemia in posttransplant HPT, in a prospective single-center study.
Methods: Nine patients with persistent hypercalcemia (>2.6 mmol/L) and stable graft function were treated with cinacalcet (30 mg/day, thereafter adapted to obtain normal serum Ca levels) for six months. Their immunosuppressive schedule included mycophenolate mofetil (MMF), steroids, and cyclosporine A (4), tacrolimus (4), or sirolimus (2).
Results: Serum Ca levels significantly decreased from 2.75+/-0.15 to 2.59+/-0.10, 2.42+/-0.29 and 2.44+/-0.25 mmol/L by one, two, and six months, respectively (P<0.02, Wilcoxon test for paired data, for all the data points). Parathyroid hormone (PTH) serum levels decreased from 171+/-102 to 134+/-63 pg/ml by two months (P<0.05) and stabilized thereafter (148+/-99 pg/ml at six months; NS). No changes in glomerular filtration rate (49.8+/-18.6 and 51.3+/-19 ml/min at initiation and six months, respectively) and no variation in serum concentration of the immunosuppressive drugs were observed. Three patients withdrew the treatment because gastrointestinal intolerance.
Conclusion: Cinacalcet allows the correction of hypercalcemia with no interference in immunosuppressive treatment or renal function. However, whether the increased intolerance observed was due to the association of cinacalcet chloride with other drugs required in renal transplantation (e.g., MMF) needs to be assessed.