Thyroid surgery: surgical and metabolic causes of hypocalcemia.

Patients undergoing radical surgical treatment of head and neck neoplasms often are seen with a history of cirrhotic liver disease, electrolyte abnormalities, and other stigma of chronic disease. Despite skillful thyroid surgical technique performed as an isolated procedure or in combination with other procedures such as laryngectomy, hypocalcemia can occur. Common causes of lowered serum calcium levels secondary to removal of parathyroid glands, blood transfusions, hypoalbuminemia, gastrointestinal malabsorption, and renal insufficiency are well known. Less well known is the recently elucidated role of dependence of calcium metabolism on magnesium. Recently, it has been well documented that alcoholism directly lowers serum magnesium levels in both human and animal models without prior liver disease or malabsorption. The fact that three mechanisms are needed to explain calcium homeostasis implies that the magnesium-calcium interdependence is not clearly understood.