vanillylmandelic

Vanillylmandelic acid (VMA) is a major metabolic end product of catecholamines in humans. It is formed during the metabolism of norepinephrine and epinephrine through enzymatic steps involving monoamine oxidase and aldehyde dehydrogenase, and is excreted in urine.

Clinically, urinary VMA measurement, typically from a 24-hour collection, has historical value in evaluating pheochromocytoma and neuroblastoma. More recently, plasma free metanephrines and urinary metanephrines are preferred for sensitivity; VMA testing is less sensitive and often used as part of broader catecholamine testing.

Dietary and pharmacological factors can affect results. Foods such as vanilla, cocoa, coffee, and certain fruits may elevate VMA. Medications including monoamine oxidase inhibitors, tricyclic antidepressants, decongestants, and nicotine can alter levels. Proper pre-test preparation and interpretation by a clinician are important.

Normal ranges vary by assay; interpretation depends on method and clinical context. Elevated VMA indicates increased catecholamine turnover but is not specific for a particular tumor; additional tests and clinical correlation are typically required.

See also: catecholamines, metanephrines, pheochromocytoma, neuroblastoma.