Metanephrine is a metabolite of epinephrine created by action of catechol-O-methyl transferase on epinephrine. A March 20, 2002 article in the Journal of the American Medical Association indicated that the measurement of plasma free metanephrines is the best tool in the diagnosis of pheochromocytoma, an adrenal medullary neoplasm.Product of epinephrine O-methylation. It is a commonly occurring, pharmacologically and physiologically inactive metabolite of epinephrine. Several clinical disorders mimic the signs and symptoms of pheochromocytoma; the definitive diagnosis of this condition thus rests primarily on showing excessive and inappropriate production of catecholamine. Because pheochromocytoma is fatal if undiagnosed, biochemical tests used to detect it should have a high sensitivity. In addition, the predictive value of any negative test result should exclude false-negative results as efficiently as possible.
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