Clinical effects of cinacalcet on biochemical parameters and bone mineral density in Japanese patients with primary hyperparathyroidism

BACKGROUND: Primary hyperparathyroidism (PHPT), characterized by hypercalcemia caused by an excessive production of parathyroid hormone from abnormal parathyroid glands, is often associated with reduced bone mineral density (BMD). The calcimimetic cinacalcet has been shown to be effective in correcting the hypercalcemia of PHPT. However, the clinical effects of cinacalcet have been scarcely reported from Japan. In this retrospective study, we evaluated the efficacy of cinacalcet in reducing serum calcium and PTH and its influence on BMD. METHODS: We analyzed the cases of 31 Japanese patients with PHPT treated with cinacalcet. We excluded six of the 31 patients who discontinued cinacalcet due to its adverse events and three patients whose cases were lost during the follow-up. RESULTS: The mean maintenance dose of cinacalcet was 31.9 +/- 13.1 mg (N.=22). Serum calcium levels decreased from 11.25 +/- 0.15 mg/dL at the baseline to 10.10 +/- 0.16 mg/dL at 6 months after the cinacalcet treatment (P<0.001). There were no significant changes in serum levels of phosphorus, intact PTH, alkaline phosphatase, or urinary calcium/creatinine ratios. T-scores before and 1 year after cinacalcet treatment were available in eight patients: the T-scores at the lumbar spine increased (-2.49 +/- 1.58 vs. -2.10 +/- 2.81, P=0.034), but not at the femoral neck (-2.22 +/- 0.61 vs. -2.20 +/- 0.76, P=0.93). CONCLUSIONS: Cinacalcet was beneficial in reducing serum calcium and seemed to be effective in increasing BMD at the lumbar spines in Japanese patients with PHPT.