The calcimimetic cinacalcet is used to treat secondary hyperparathyroidism in patients receiving dialysis, and asymptomatic hypocalcemia is often observed following its initiation. Here we investigated the incidence, predictors and therapeutic consequences of hypocalcemia by a post hoc analysis of the randomized, double-blind, placebo-controlled EValuation Of Cinacalcet Hydrochloride Therapy to Lower CardioVascular Events (EVOLVE) trial. Hypocalcemia was classified as mild (total serum calcium 8.0-8.39 mg/dL), moderate (7.5-7.99 mg/dL) or severe (under 7.5 mg/dL). At least one episode of hypocalcemia developed within 16 weeks after the first administered dose among 58.3% of 1938 patients randomized to cinacalcet versus 14.9% of 1923 patients randomized to placebo. Hypocalcemia in the cinacalcet group was severe in 18.4% of the patients versus 4.4% in the placebo group. Severe hypocalcemia following administration of cinacalcet was associated with higher baseline plasma parathyroid hormone, lower corrected total serum calcium, higher serum alkaline phosphatase, geographic region (patients from Latin America and Russia had a higher risk relative to the United States) and higher body mass index. The median cinacalcet dose immediately prior to the first hypocalcemic episode was 54-58 mg/day and similar in the three hypocalcemia categories. In the majority of patients, hypocalcemia resolved spontaneously within 14 days without modification of background therapy. Among patients who received an intervention, the most common was an increase in the active vitamin D sterol dose. Thus, the occurrence of hypocalcemia is frequent following initiation of cinacalcet and the likelihood of developing hypocalcemia was related to the severity of secondary hyperparathyroidism. Hypocalcemia was generally asymptomatic and self-limited.
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