Endocrine Abstracts

Although primary hyperparathyroidism (PHPT) is usually cured by surgery, some individuals are unable to undergo parathyroidectomy and are refractory to standard calcium lowering medical therapy. In such cases, targeted therapy with cinacalcet may be useful.

The aim of this study was to access the short-term efficacy of cinacalcet in lowering calcium (Ca²⁺) levels in patients with PHPT unable to undergo parathyroidectomy and refractory to standard medical therapy.

Methods

Patients with PHPT refractory to standard medical treatment were treated with cinacalcet. Statistical analysis was carried out using the Wilcoxon test.

Results

Five patients (all female) with a median age of 76 years were included. The known duration of the PHPT was 60 months. The median follow-up of cinacalcet treatment was 12 months. Hypercalcemia related comorbidities were mental changes in 4, osteoporosis in 3 and kidney stones in 2 patients. Before medical treatment, baseline median (quartile 1 (Q1), Q3) serum PTH was 252 (159, 614) pg/ml (reference range 15–65) and serum Ca²⁺ was 11.7 (11.6, 12.65) mg/dl (reference range 8.1–10.2). After standard medical treatment, baseline median (quartile 1 (Q1), Q3) serum PTH was 222 (149, 304) pg/ml and serum Ca²⁺ was 11.9 (11.2, 12.6) mg/dl (P>0.05). After the last stable dose of cinacalcet, median (quartile 1 (Q1), Q3) serum PTH was 190 (139, 361) pg/ml and serum Ca²⁺ was 10.1 (9.7, 12) mg/dl (P=0,005). Serum Ca²⁺ normalized in 60% of patients. The median decrease of Ca²⁺ was 15.1% (P=0,005) and of PTH was 14.4% (P=0,174). Only one patient developed side effects (muscle spasms) without the need to stop cinacalcet.

Conclusions

These results demonstrate the efficacy and safety of cinacalcet in controlling hypercalcemia refractory to standard medical therapy.