Plasma metanephrines: a novel and cost-effective test for pheochromocytoma

Pheochromocytomas are rare chromaffin cell tumors that nevertheless must be excluded in large numbers of patients who develop sustained or episodic hy pertension as well as in many others with suggestive symptoms or with a fam ilial history of pheochromocytoma. Diagnosis of pheochromocytoma depends im portantly on biochemical evidence of excess catecholamine production by a t umor. Imperfect sensitivity and specificity of commonly available biochemic al tests and the low incidence of the tumor among the tested population mea n that considerable time and effort can be expended in confirming or ruling out pheochromocytoma in patients where the tumor is suspected. Measurement s of plasma free metanephrines provide a superior test compared to other av ailable tests for diagnosis of pheochromocytoma. In particular, the high se nsitivity of plasma free metanephrines means that a normal test result reli ably excludes all but the smallest of pheochromocytomas so that no other te sts are necessary. Measurements of plasma free metanephrines, when systemat ically combined with other diagnostic procedures outlined in this review, p rovide a more efficient, reliable and cost-effective approach for diagnosis of pheochromocytoma than offend by previously available approaches.