Graves' Disease Accompanied by Pheochromocytoma: Report of a Case

We present here a rare case of Graves' disease accompanied by pheochromocytoma, and the patient showed normal urine and serum levels of catecholamines and their metabolites. A 45-year-old woman was referred to our hospital for the evaluation of a right adrenal incidentaloma that was detected by chest computed tomography. She had been diagnosed with Graves' disease 1 month previously. She had no symptoms of pheochromocytoma such as hypertension or a history of hypertension attack. Two consecutive 24-hour urine samples were sent to the lab for measurement of the catecholamines, and both samples showed normal levels of metanephrine and vanillylmandelic acid (VMA). After right adrenalectomy was performed, the final pathological diagnosis was adrenal pheochromocytoma. This case suggests that the onset of Graves' disease may be associated with excess catecholamine secreted by a pheochromocytoma. In addition, although the conventional method for detecting pheochromocytoma is to identify an increase of the urine catecholamines, physicians should be aware of the possibility of false negativity on this test. (J Korean Endocr Soc