Vanillylmandelic Acid
Overview
Vanillylmandelic acid (VMA) measures the primary urinary metabolite of catecholamines (epinephrine, norepinephrine) and their metabolites, reflecting adrenal medullary and neural crest tumor activity. It serves as a biochemical marker of catecholamine production from tyrosine via chromaffin cell tumors. Elevated levels indicate pheochromocytoma, neuroblastoma, or ganglioneuroma, while normal levels effectively exclude these diagnoses; clinically useful for diagnosing and monitoring neural crest tumors, particularly neuroblastoma screening in children with abdominal masses or hypertension.
Clinical Use Cases
- Diagnosing pheochromocytoma/paraganglioma.
- Neuroblastoma screening and monitoring.
- Evaluating ganglioneuroblastoma and ganglioneuroma.
- Assessing metastatic neural crest tumors.
- Monitoring chemotherapy response in neuroblastoma.
Specimen Types
- 24-hour urine collection.
- Random urine (spot VMA/creatinine ratio).
Measurement Methods
- High-performance liquid chromatography (HPLC) with electrochemical detection.
- Gas chromatography-mass spectrometry (GC-MS).
- Colorimetric assay (older method).
Test Preparation and Influencing Factors
- Avoid bananas, vanilla, caffeine, acetaminophen 72 hours prior.
- 24-hour urine collection with acid preservative (6N HCl).
- Stress, exercise, clonidine withdrawal elevate levels.
- Collect during catecholamine surge if intermittent secretion suspected.
- Infantile neuroblastoma may show normal VMA.
Synonyms
- VMA.
- 4-hydroxy-3-methoxymandelic acid.