A single centre retrospective analysis of cinacalcet therapy in primary hyperparathyroidism

Primary hyperparathyroidism (pHPT) is a common endocrine disorder that can be cured by parathyroidectomy, and patients unsuitable for surgery can be treated with cinacalcet. Availability of surgery may be reduced during COVID-19 and cinacalcet can be used as bridging therapy. In this single centre retrospective analysis, we investigated the efficacy and safety of cinacalcet in patients with pHPT receiving cinacalcet between March 2019 and July 2020, including pre-parathyroidectomy bridging. We reviewed and summarised the published literature. 86 patients were identified, with most achieving target calcium (79.1%) with a mean dose of 39.4 mg/day for a median duration of 35 weeks. Calcium normalised in a median time of 5 weeks. The majority of patients commenced cinacalcet 30 mg/day (78; 90.7%) with the remainder at 60 mg/day (8; 9.3%). 57.8% of patients commenced on lower dose cinacalcet (30 mg/day) achieved a target Ca without requiring 60 mg/day. Baseline PTH was significantly higher in patients requiring higher doses of cinacalcet (p=0.014). 18.6% of patients reported adverse reactions and 4.7% discontinued cinacalcet. Patients treated with cinacalcet pre-parathyroidectomy required a higher dose and fewer achieved target calcium compared to those treated medically with cinacalcet alone. Post-operative calcium was similar to patients not given pre-parathyroidectomy cinacalcet. In summary, cinacalcet at an initial dose of 30 mg/day is safe and effective for achieving target calcium in patients with symptomatic or severe hypercalcaemia in pHPT, including those treated pre-parathyroidectomy. We propose a PTH threshold of >30 pmol/L to initiate at a higher dose of 60 mg/day.