Malignancy-related hypercalcemia developing on a bisphosphonate but responding to calcitonin.

Bisphosphonates are considered a cornerstone for the treatment of hypercalcemia of malignancy, whereas calcitonin has not been found to be as potent. We report a case of severe hypercalcemia of malignancy that developed while the patient was taking alendronate that responded to the use of calcitonin. A 73-year-old woman developed hypercalcemia of malignancy while taking weekly alendronate. The patients' serum calcium remained above 15 mg/dL despite hydration and loop diuretics for 48 hours in addition to the bisphosphonates, and resistance was suspected. Intravenous calcitonin produced a dramatic decrease within 12 hours and normal serum calcium within 24 hours of treatment. Calcitonin might be useful for hypercalcemia of malignancy resistant to bisphosphonates.