Treatment of severe hypercalcemia due to refractory hyperparathyroidism in renal transplant patients with the calcimimetic agent cinacalcet

Calcimimetic agents increase the sensitivity of calcium sensing receptors of parathyroid glands and suppress both serum calcium levels and parathyroid hormone. There are still limited data on the treatment of renal transplant patients with severe hypercalcemia and hyperparathyroidism with calcimimetics (cinacalcet). We describe two such renal transplant patients with chronic kidney disease Stage 3 who presented with persistent hypercalcemia (serum calcium 11.5-12 mg/dl) and refractory hyperparathyroidism (iPTH 194-547 pg/ml). Control of hypercalcemia with cinacalcet (serum calcium <10 mg/dl) resulted also in an improvement of hyperparathyroidism, but with a slower rate than that of the lowering of serum calcium. Addition of a vitamin D analog together with the calcimimetic agent resulted in faster control of the resistant hyperparathyroidism in both patients (iPTH <145 pg/ml) with clinical improvement and without any side effect. It seems that this new agent will improve our clinical approach of renal bone disease permitting a more integrated and successful treatment of hyperparathyroidism and its consequences on patients with chronic kidney disease.