Endocrine Abstracts

Introduction: Cinacalcet acts at the calcium-sensing receptors on parathyroid cells to increase the sensitivity to circulating calcium concentrations. Studies have shown that this treatment is an effective means of managing hypercalcaemia in primary hyperparathyroidism.

Aims: The aim of this study was to determine the outcomes of patients who had received cinacalcet for at least 3 months for primary hyperparathyroidism.

Methods: We identified patients who had a diagnosis of primary hyperparathyroidism and who had been treated with cinacalcet for at least 3 months. Patients with renal disease were excluded from the study.

Results: 12 patients were identified with a mean age 75.8 years, 10 males, 2 females. Two patients were admitted because of their hypercalcaemia. Two patients underwent parathyroid surgery after commencing cinacalcet which was subsequently discontinued.

Calcium and PTH data

Pretreatment PTH range was 43–838 ng/l, median 150 ng/l. Pretreatment calcium range was 2.66–3.77 mmol/l, median 3.01 mmol/l. All 12 patients had an improvement in calcium levels with 6 patients achieving normocalcaemia. Three additional patients achieved calcium levels between 2.6 and 2.8 mmol/l. Median fall in calcium levels was 0.455 mmol/l (0.27–0.71 mmol/l). There was no correlation between initial PTH level and percentage fall in calcium levels. (correlation coefficient r=0.378, P=0.225) nor between initial calcium levels and percentage fall in calcium levels (correlation coefficient r=0.007, P=0.9).

Discussion: Our results are consistent with evidence in the literature that shows that cinacalcet results in biochemical improvement in calcium levels, with all subjects showing significant falls in calcium levels (between 9 and 20%) (P=0.002). The absence of an association between initial PTH and calcium levels with the subsequent reduction in calcium levels suggests that improvements in calcium levels cannot be predicted based on these two measurements alone. We recommend this treatment as an alternative to surgery for primary hyperparathyroidism in patients with significant symptomatic hypercalcaemia unresponsive to conventional interventions.