Hypoglycemia as a complication of removal of a pheochromocytoma

In a patient with a solitary pheochromocytoma severe hypoglycemia developed following excision of the tumour. The possible causative mechanism was thought to be a reactive relative increase in insulin production secondary to increased endogenous production of glucose, induced by the large amounts of epinephrine produced by the tumour. Alternatively, epinephrine withdrawal following removal of the tumour under phentolamine infusion may have induced increased insulin production and hence potentiated the development of hypoglycemia. Careful monitoring of the blood glucose concentration during and after the operation is recommended to obviate this potentially fatal complication.