Effects of cinacalcet on bone mineral density in patients with secondary hyperparathyroidism

Cinacalcet, a calcimimetic agent, is effective in treating both primary and secondary hyperparathyroidism. Because hyperparathyroidism induces mineralized bone loss, we investigated the effects of cinacalcet treatment on bone mineral density (BMD) in patients with secondary hyperparathyroidism due to chronic kidney disease.

Ten patients who were receiving haemodialysis and four patients, who had stage 4 chronic kidney disease participated and completed the multicentre, randomized, double-blind, placebo-controlled trials evaluating the safety and efficacy of cinacalcet for treating secondary hyperparathyroidism. The efficacy of cinacalcet was assessed by plasma intact parathyroid hormone (iPTH) levels. A dual energy X-ray absorptiometry was performed to measure the BMD of total proximal femurs and lumbar spine (L2-L4) before and after 26 weeks of treatment.

Cinacalcet reduced iPTH from 912+/-296 to 515+/-359 pg/ml in haemodialysis patients and from 210+/-46 to 56+/-51 pg/ml in pre-dialysis patients (means+/-SD; both P<0.05). When data from haemodialysis and pre-dialysis patients were pooled for analysis, cinacalcet treatment increased proximal femur BMD from 0.945+/-0.169 to 0.961+/-0.174 g/cm(2) (P<0.05), but did not affect lumbar spine BMD. There was a correlation between the change in femur BMD and the change in iPTH during the study period (R(2) = 0.39, P<0.05).

Secondary hyperparathyroidism is associated with progressive bone loss. Suppression of plasma iPTH with cinacalcet appears to reverse bone loss in the proximal femur, but does not affect BMD of the lumbar spine. A larger study is warranted to confirm that cinacalcet has a beneficial effect on the skeletal system in patients with secondary hyperparathyroidism.