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

Abstract

Our experience with low-dose cinacalcet to normalize serum calcium in patients with primary hyperparathyroidism (PHPT) not eligible for surgery is reported. The impact of this drug on various parameters of calcium-phosphorus metabolism and its tolerability profile were analyzed.Seventeen patients diagnosed with PHPT who had hypercalcemia and also met one or more of the inclusion criteria of high risk of parathyroidectomy, persistent/recurrent PHPT after previous parathyroid surgery, or refusal of surgery were recruited.The starting cinacalcet dose was 30 or 60mg/day, and dosage was adjusted based on the degree of calcemia reduction and drug tolerability.A decrease in serum calcium levels was already evident in the first post-treatment test. Appropriate dose adjustment was performed when required, and normal serum calcium levels were achieved in a majority of patients and remained stable during follow-up.Parathyroid hormone levels decreased but were not normalized in most patients. Urine calcium levels decreased, while serum phosphate and alkaline phosphatase levels increased. Cinacalcet tolerability was usually good at the doses used. The most common adverse effects included weakness, dizziness, and asthenia, but led to treatment withdrawal in only one patient.It was concluded that low-dose cinacalcet effectively decreases serum calcium levels, normalizes calcium levels in a majority of patients with PHPT not eligible for surgical treatment, and has a good tolerability profile.