Dual-mediated PTH and Osteolytic Hypercalcemia in Metastatic Endometrial Carcinoma

Hypercalcemia of malignancy (HCM) occurs frequently in advanced stage cancer and can be secondary to many different etiologies. This case illustrates a rare case of dual-mediated PTH and osteolytic HCM in the setting of metastatic endometrial carcinoma. The patient's hypercalcemia was refractory to initial treatment with IV hydration, calcitonin, and zoledronic acid, eventually requiring the addition of denosumab therapy and cinacalcet. After 15 days of treatment, the patient's calcium concentration returned to normal levels. Owing to elevated PTH levels, other etiologies of hypercalcemia were not initially investigated. Bone metastases, which were not observed on admission computed tomography, were incidentally identified on the technetium-99 m sestamibi scan. This case illustrates that although concurrent etiologies of hypercalcemia are uncommon, it is important to evaluate all possible contributing causes, especially in the clinical setting of malignancy.