Tetany by transfusion of small volume of blood: a rare case report.

A requisition for two units of packed red blood cells was received for a 54 year female, known case of genitourinary carcinoma. After transfusion of approximately 15-20 ml of blood, a call was received from resident in charge of radiotherapy ward stating that patient had clenching of hands along with circumoral tingling and paresthesias in her limbs. Her investigations showed decreased serum potassium and calcium levels but serum magnesium levels were not available. Multiple electrolyte disturbances probably precipitated tetany even by small volume of blood transfusion. We therefore recommend careful monitoring of electrolytes, including magnesium, before starting blood transfusion.