Vanillylmandelic Acid Urine Test
From Health Facts
Latest Edit: Hector 2014-03-21 (EDT)
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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.
- 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
- Dietary restrictions may be required
- Factors which can cause increased levels:
- 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
High levels indicate:
- Severe stress
- Strenuous exercise
- Acute anxiety
Low levels indicate:
- None indicated
- Pheochromocytoma suppression and provocative tests
- Pagana Kathleen D, Pagana Timothy J (2006) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby.