Normalization of lithium-induced hypercalcemia and hyperparathyroidism with cinacalcet hydrochloride

An underrecognized side effect of long-term lithium carbonate therapy is hyperparathyroidism with associated hypercalcemia and hypocalciuria. Because cessation of lithium carbonate therapy usually does not correct the hyperparathyroidism and associated hypercalcemia, parathyroidectomy frequently is necessary. This is the initial report of 2 patients with lithium carbonate-induced hyperparathyroidism treated with cinacalcet hydrochloride (HCl), which normalized serum calcium levels and reduced intact parathyroid hormone (iPTH) secretion. The patients, both with bipolar disease and a 15- to 30-year history of lithium carbonate therapy, were evaluated for stage 3 chronic kidney disease, persistent hypercalcemia, and hyperparathyroidism. A 67-year-old woman was administered cinacalcet HCl, 30 mg/d, for 11 months. Mean serum calcium level decreased from 10.8 +/- 0.4 mg/dL (2.69 +/- 0.10 mmol/L) to 9.9 +/- 0.4 mg/dL (2.47 +/- 0.10 mmol/L; P < 0.001), and iPTH level decreased from 139 +/- 31 pg/mL (139 +/- 31 ng/L) to 114 +/- 39 pg/mL (114 +/- 39 ng/L; P = not significant). A 63-year-old man was administered 30 mg/d of cinacalcet HCl for 8 months, then 60 mg/d for another 2 months. Mean serum calcium and iPTH levels decreased from 11.0 +/- 0.5 mg/dL (2.74 +/- 0.12 mmol/L) to 10.3 +/- 0.4 mg/dL (2.57 +/- 0.10 mmol/L; P < 0.001) and 138 +/- 10 pg/mL (138 +/- 10 ng/L) to 73 +/- 7 pg/mL (73 +/- 7 ng/L; P = 0.03), respectively. Urinary fractional excretion of calcium was low for both patients before (<0.026 and <0.015) and after (0.026 and 0.008) treatment with cinacalcet HCl. These findings suggest that cinacalcet HCl can provide an alternative nonsurgical means to control this disorder in patients with hypercalcemia of variable severity for whom surgical treatment is not a consideration because of perceived mildness of disease or unsuitability of the patient for surgical intervention.