In this module, we outline the approach to a patient who may have hypocalcemia. You will learn the basics of calcium homeostasis and the reasons serum calcium levels can decrease when a dysfunction occurs. Important questions to ask in a history including onset, timing and associated symptoms, if any, are discussed. With presentations that range from incidental lab finding, to overt cardiac disease, a systematic approach is essential in the work up of these patients. Investigative modalities are directed by clinical impression. Management is two-fold, aimed at managing symptoms and treating the cause of low serum calcium.