Prolonged zoledronic acid-induced hypocalcemia in hypercalcemia of malignancy.

Zoledronic acid is a parenteral long-acting bisphosphonate that has been shown to be more effective than other bisphosphonates in treating hypercalcemia of malignancy. It is important to be aware of its ability to induce prolonged and severe hypocalcemia (hypoCa) following administration, which can be difficult to control despite aggressive calcium replacement. We report on a patient with metastatic breast cancer who presented with severe symptomatic hypoCa after receiving zoledronic acid for hypercalcemia of malignancy.