Vanilmandelic acid

Vanilmandelic Acid (VMA) is a metabolite of the catecholamines epinephrine (also known as adrenaline) and norepinephrine (noradrenaline). It is produced when the body breaks down these catecholamines. The measurement of VMA levels in the body is often used in the diagnosis and management of certain medical conditions, particularly those involving the adrenal glands.

Biochemistry

Vanilmandelic acid is the end product of a series of biochemical reactions that begin with the amino acid phenylalanine. Phenylalanine is converted into tyrosine, which is then converted into dopa. Dopa is converted into dopamine, which is then converted into norepinephrine and epinephrine. These catecholamines are broken down into metanephrine and normetanephrine, which are further metabolized into VMA.

Clinical Significance

The measurement of VMA levels in the urine is a common diagnostic test for pheochromocytoma, a rare tumor of the adrenal glands that produces excess amounts of catecholamines. Elevated levels of VMA in the urine are indicative of this condition. This test is also used in the diagnosis and management of neuroblastoma, a type of cancer that often affects children and is derived from neural crest cells.

Measurement

VMA levels are typically measured in a 24-hour urine sample. The patient is instructed to collect all urine produced over a 24-hour period, which is then analyzed in a laboratory. The results are usually reported as milligrams of VMA per 24 hours.

See Also

• Catecholamines
• Pheochromocytoma
• Neuroblastoma
• Adrenal glands