Hypoglycemia following excision of pheochromocytoma

In two patients hypoglycemia developed in the immediate postoperative period after removal of a pheochromocytoma. In one patient the serum insulin value was elevated when he was hypoglycemic. Preoperative preparation of patients with pheochromocytoma requires use of an alpha-adrenergic blocking agent to decrease blood pressure and allow the plasma volume to expand; in the two patients referred to phenoxybenzamine was given orally. It is difficult to recognize hypoglycemia postoperatively because of the altered consciousness associated with a major operation, analgesics, anesthetic agents and the effects of adrenergic blocking medications; hence the physician must watch closely for this complication.