Control of Refractory Hypercalcemia with Denosumab in a Case of Metastatic Parathyroid Carcinoma

Parathyroid carcinoma is a rare cause of hyperparathyroidism and leads to severe hypercalcemia. The etiology is not fully known. Parathyroid cancer should be considered in the differential diagnosis, if serum calcium and parathyroid hormone levels increase, and parathyroid gland is palpable. Severe hypercalcemia is the most common cause of death in patients diagnosed with parathyroid carcinoma. Fluid replacement, diuretic therapy, bisphosphonates, and calcimimetic agents are the main treatment steps in the control of life-threatening hypercalcemia. Surgery is the primary treatment option, while denosumab is a treatment option for refractory hypercalcemia caused by parathyroid carcinoma, or for patients who are not eligible for surgery. There are few case reports in literature about denosumab treatment for parathyroid carcinoma. Herein, we report a case of a patient who presented with the complaint of leg pain and was diagnosed with parathyroid carcinoma. The elevated calcium level of the patient was controlled with denosumab. Key Words: Parathyroid carcinoma, Denosumab, Hypercalcemia, Hyperparathyroidism.