Pheochromocytoma with elevated metanephrines as the only biochemical finding

Pheochromocytoma is usually diagnosed by finding elevated levels of metanephrines, catecholamines, or vanillylmandelic acid in 24-hour urine collections. At least two of the three urine analytes are usually elevated. We found no report of a documented pheochromocytoma in which only one of the three analytes was elevated. Herein we report a patient with severe hypertension and a right adrenal mass, who was found on repeated testing to have only elevated urinary metanephrines. The 24-hour urine collections for vanillylmandelic acid, total catecholamines, fractionated catecholamines, and urine dopamine were all normal. The patient underwent surgery for the right adrenal mass, and the pathology report confirmed the diagnosis of pheochromocytoma.