Vanillylmandelic Acid Urine Test

Latest Edit: Hector 2014-03-21 (EDT)

See Also	Lab Tests

This is a 24-hour urine test that is performed to diagnose hypertension secondary to pheochromocytoma. It is used to detect the presence of neuroblastomas and other rare adrenal tumors.

Discussion

• VMA is the product of catabolism of both metanephrine and normetanephrine
• In a pheochromocytoma, or tumor of the chromaffin cells within the adrenal medulla, one or all of these substances will be present in excessive quantities in a 24-hour urine collection.
• VMA is more easily detected due to the concentration being higher than any one catecholamine component

Patient Preparation

• Dietary restrictions may be required

• Factors which can cause increased levels:

• certain foods such as tea, coffee, cocoa, vanilla, chocolate, cider vinegar, soda, licorice, vigorous exercise, stress, starvation
• Drugs: caffeine, epinephrine, levodopa, lithium, nitroglycerin

• Factors which can cause decreased levels:

• uremia, alkaline urine, and radiographic iodine contrast agents
• Drugs: clonidine, disulfiram, guanethidine, imipramine, monoamine oxidase (MAO) inhibitors, phenothiazines, reserpine

Clinical Implications

High levels indicate:

• Pheochromocytomas
• Neuroblastomas
• Ganglioneuromas
• Ganglioblastomas
• Severe stress
• Strenuous exercise
• Acute anxiety

Low levels indicate:

• None indicated

Associated Tests

• Pheochromocytoma suppression and provocative tests