Endocrine Abstracts

We present a rare case of Graves’ disease accompanied by pheochromocytoma, which 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 detected by computed tomography. She was diagnosed with Graves disease at 6 months ago. Initially she got an antithyroid medication include methimazole, but her thyroid function could not control easily. So, radioactive iodine therapy was performed then her thyroid function returned normal values. She had no symptoms of pheochromocytoma such as hypertension or a history of hypertension attack. Two consecutive 24-hour urine samples were sent for measurement of catecholamines, both of which showed normal levels of free cortisol, metanephrine, VMA, epinephrine and norepinephrine. After right adrenalectomy was performed, the final pathologic diagnosis was adrenal pheochromocytoma. This case suggests that the Graves’ disease may be associated with excess catecholamine secreted by pheochromocytoma. In addition, although the conventional method for detecting pheochromocytoma is to identify an increase in urine catecholamines, physicians should be aware of the possibility of false negativity.