Vanillylmandelic Acid, 24 Hr, U
Use
Vanillylmandelic acid (VMA) and other catecholamine metabolites, such as homovanillic acid (HVA) and dopamine, are typically elevated in patients with catecholamine-secreting tumors (eg, neuroblastoma, pheochromocytoma, and other neural crest tumors). More than 90% of individuals with neuroblastoma have elevated VMA and/or HVA. This test is useful for screening children for catecholamine-secreting tumors when requesting testing for VMA only, supporting diagnosis of neuroblastoma, and monitoring treated neuroblastoma patients. VMA is not preferred for detection of pheochromocytoma; metanephrines are better detected via specific tests. Treatment with L‑dopa may impact test results and should be discontinued 24 hours prior to collection. Bactrim may also interfere and should be noted at time of collection.
Special Instructions
Patient’s age, collection duration (hours), and urine volume (milliliters) are required when ordering. All patients receiving L‑dopa or taking Bactrim should be identified when the test is ordered. If not ordering electronically, an Oncology Test Request (T729) form must be completed and sent. Recommended specimen preservation: add 25 mL of 50% acetic acid at the start of collection (15 mL for children under 5 years). If refrigerated during collection, preservative may be added up to 12 hours after starting. Preserve urine to pH 1–5; if necessary, adjust pH dropwise with 50% acetic acid or hydrochloric acid. For multiple collections, refer to Urine Preservatives-Collection and Transportation for 24‑Hour Urine Specimens.
Limitations
A positive result does not confirm presence of a catecholamine‑secreting tumor; a normal result does not exclude it. VMA is less sensitive in pheochromocytoma detection. Additional confirmatory testing may be required. Analytical or interpretive limitations beyond these are not explicitly stated.
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
LOINC Codes
- 43099-1
- 3122-9
- 30571-4
- 13362-9
- 3167-4
Result Turnaround Time
2-4 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
5 mL
Minimum Volume
2 mL
Container
Clean, plastic urine collection container; submission in 10‑mL urine tube
Collection Instructions
Add 25 mL of 50% acetic acid at start (15 mL for children <5 y). Collect 24‑hour urine. If necessary, adjust pH 1–5 with acid dropwise.
Patient Preparation
Discontinue L‑dopa for 24 h prior to collection; note Bactrim use.
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 28 days |
| Frozen | 180 days |