Severe Hypocalcemia After the Administration of Zoledronic Acid for Osteoporotic Fracture

Abstract

Zoledronic acid is a potent intravenous bisphosphonate used in the treatment of osteoporosis and malignancy-induced hypercalcemia or bone metastasis. Although zoledronic acid generally seems to be safe and well-tolerated, rare but life-threatening nephrotoxicity or hypocalcemia may occur. The majority of cases of hypocalcemia with zoledronic acid have been seen in patients with underlying malignancy and are asymptomatic or mild. Vitamin D deficiency, renal failure, hypoparathyroidism, and hypomagnesemia have been reported as risk factors for hypocalcemia. Here, the author reports a case of severe symptomatic hypocalcemia following the administration of zoledronic acid for the treatment of osteoporotic fracture. This patient also had underlying but unrecognized vitamin D deficiency and chronic kidney disease. Following the administration of calcium and vitamin D, her symptoms improved and calcium levels returned to normal within several days. To avoid serious hypocalcemia with zoledronic acid, calcium and vitamin D status and renal function should be assessed and corrected if appropriate.