Incidence and predictive factors of hypoglycemia after pheochromocytoma resection

To determine the incidence and preoperative risk factors of post-excisional hypoglycemia in patients undergoing pheochromocytoma resection.

Patients who underwent surgical resection of pheochromocytoma at a single institution were retrospectively enrolled in the present study. The primary end-point was the development of post-excisional hypoglycemia; that is, a serum glucose level <70 mg/dL. The serum levels of immunoreactive insulin and glucose levels during the preoperative oral glucose-tolerance test and surgery were analyzed to elucidate the mechanism of hypoglycemia.

A total of 49 patients underwent surgical resection of pheochromocytoma, of which 21 patients (43%) developed post-excisional hypoglycemia. The incidence of hypoglycemia was not statistically different between patients with adrenal tumors and those with extra-adrenal tumors (18/41 [44%] vs 3/8 [38%], respectively, P = 0.73). There was no difference in the immunoreactive insulin/glucose ratio during the preoperative oral glucose-tolerance test between patients with and those without post-excisional hypoglycemia. The intraoperative immunoreactive insulin/glucose ratio was significantly higher in patients with hypoglycemia than in those without hypoglycemia. A higher 24-h urinary epinephrine level, but not norepinephrine level, was a predictive factor for post-excisional hypoglycemia.

Post-excisional hypoglycemia is a frequent complication of pheochromocytoma resection, irrespective of the tumor location, and might be common in patients with epinephrine-predominant tumors. All patients undergoing resection of adrenal and extra-adrenal pheochromocytoma require intensive monitoring of serum glucose levels during and after surgery.