SAT-202 Hypoglycemia Following Unilateral Pheochromocytoma Resection in the Immediate Post-Surgical Period

Introduction Hypoglycemia in the immediate post-resection period of unilateral pheochromocytoma is a potential complication but not very well recognized. Clinical Case A 47 year old female with past medical history of Hypertension, coronary artery disease, Myocardial infarction, Depression, Systemic lupus erythematosus presented to the hospital initially for elective robotic assisted Left adrenalectomy. CT scan showed a big left adrenal mass with normal right adrenal gland. It was clinically diagnosed as Pheochromocytoma as outpatient by primary internist. Biochemical studies showed elevated serum metanephrines and normetanephrines, and urine normetanephrine. Post-surgery (< 24 hours) patient had episodes of fasting hypoglycemia with blood glucose levels as low as 68 mg/dl, accompanied with neuroglycopenic symptoms like tremors, sweating and palpitations. High dose ACTH stimulation test was performed. Serum cortisol levels were tested as 5.1, 11.7 and 14.4 mcg/dl within 0, 30 minutes and 60 minutes of Cosyntropin 250 mcg IV injection. The patient was started on Prednisone 5 mg daily to prevent any further episodes, which was successful, and was stopped by the patient one week after discharge, without any more hypoglycemia episodes. Further endocrinology work up could not be done as the patient did not follow up. Post-surgical pathology showed a 7x 5.5 x4 cm mass, which was confirmed as pheochromocytoma histopathologically and immunohistochemically by positive chromogranin, synaptophysin and BCl2 and negative for calretinin and S100. Discussion and Conclusion The etiology of hypoglycemia after resection of unilateral pheochromocytoma can be explained by impaired glucagon secretion and decreased gluconeogenesis due to the suppression from higher catecholamine levels in the blood pre-operatively. The second mechanism is rebound insulin secretion from the pancreas due to sudden withdrawal of catecholamines. In our patient, the transient hypocortisolemia could be another reason. The lack of immunohistochemical evidence in post-surgical pathology report excluded cortisol- secreting tumor. Another rare situation, ACTH-secreting pheochromocytoma, has been reported but was not checked in the case. In a word, hypoglycemia is common after surgical removal of unilateral pheochromocytoma. Careful monitoring of patients’ glucose level in immediate post-resection period is essential to prevent transient hypoglycemia References 1.Akiba M, Kodaba T, Ito Y, Obara T, Fujimoto Y. Hypoglycemia induced by excessive rebound secretion of insulin after removal of pheochromocytoma. World J Surg; 14(3):317-24 2.Chen Y, Hodin RA, Pandolfi C, Ruan DT, McKenzie TJ. Hypoglycemia after resection of pheochromocytoma.Surgery;156(6): 1404-09