Clinical Utility

Measurements of either plasma free metanephrines or 24 hour urinary fractionated metanephrines are recommended for screening for pheochromocytomas and paragangliomas (Nat Clin Pract Endocrinol Metab, Feb 2007, 3(2):92-102).  Metanephrines are metabolites of catecholamines that have demonstrated higher sensitivity and specificity for detecting pheochromocytomas than measurement of either plasma or urinary catecholamines, particularly when an age-appropriate reference range is available (J Clin Endocrinol Metab, May 2002, 87(5):1955–1960).  To our knowledge, there is no literature suggesting that combining catecholamine testing with metanephrine testing adds any value over metanephrine testing alone.