Severe Hypocalcemia after Intravenous Bisphosphonate Therapy in Occult Vitamin D Deficiency

Abstract

Oral bisphosphonates are effective for the prevention and treatment of osteoporosis. Powerful second- and third-generation parenteral bisphosphonates, including pamidronate and zoledronate, are also available for off-label use. Although rarely observed, mild hypocalcemia has been reported with this class of agents.¹ On the other hand, osteomalacia, as a result of vitamin D deficiency, is common, especially in elderly persons and those with malabsorptive states such as those due to gastric bypass, nontropical sprue, and cystic fibrosis.² A recent case illustrates a serious complication of bisphosphonate use in a patient with coexisting but occult osteomalacia.