[Low-dose cinacalcet reduces serum calcium in patients with primary hyperparathyroidism not eligible for surgery].

We present our experience with low-dose cinacalcet to normalize serum calcium in patients with primary hyperparathyroidism (PHPT) not eligible for surgery. We analyzed the impact of this drug on various parameters of calcium-phosphorus metabolism and its tolerability profile. We recruited 17 patients diagnosed with PHPT who had hypercalcemia and also met one or more of the following inclusion criteria: elevated risk for parathyroidectomy, persistent/recurrent PHPT after previous parathyroid surgery or refusal to undergo surgery. The starting dose of cinacalcet was 30 or 60 mg/day, which was adjusted depending on the degree of calcemia reduction and tolerance to the drug. We observed a reduction in serum calcium that was already evident in the first post-treatment test. Appropriate dose adjustment was performed when required and normal serum calcium levels were achieved in most patients, remaining stable during follow-up. Parathyroid hormone was reduced but not normalized in most patients. Calciuria decreased while serum phosphate and alkaline phosphatase levels increased. Cinacalcet tolerance was generally good at the doses used. The most common adverse effects were weakness, dizziness and asthenia, leading to treatment withdrawal in only one patient. We conclude that low-dose cinacalcet reduces serum calcium efficiently, normalizes calcium levels in most patients with PHPT not eligible for surgical treatment and has a good tolerability profile.