Unusual Cause of Hypocalcemia

Abstract

Introduction Hypocalcemia is a known side effect of regorafenib, however, the mechanism is poorly understood. Regorafenib is a new tyrosine kinase inhibitor approved by the US Food and Drug Administration (FDA) for treatment of metastatic colorectal cancer. This report describes a case of profound hypocalcemia potentially related to the use of regorafenib in a patient with metastatic colon cancer. The etiology of hypocalcemia is not clearly published in the English literature. This case illustrated the importance of monitoring calcium and phosphate levels in patients who are on a tyrosine kinase inhibitor to avoid potential lethal toxicity.