Abnormally low blood calcium. This condition occurs transiently in patients with severe sepsis, severe pancreatitis, burns, and acute renal failure. It also may result from multiple transfusions with citrated blood, parathyroidectomy, malabsorption, and medications such as protamine, heparin, and glucagon. Chronic hypocalcemia may be caused by chronic renal failure, hypoalbuminemia, and malnutrition. Clinical manifestations in chronic hypocalcemia include muscle spasm, carpopedal spasm, facial grimacing, possible convulsions, and mental changes such as irritability, depression, and psychosis. Treatment consists of calcium infusions and appropriate therapy for the causative disease.