5-Hydroxyindoleacetic Acid, 24 Hour, Urine
Use
Measurement of urinary 5-hydroxyindoleacetic acid (5-HIAA), the major metabolite of serotonin excreted in urine, is useful for biochemical diagnosis and monitoring of intestinal carcinoid syndrome and neuroendocrine tumors. Elevated excretion of 5-HIAA in a properly collected 24‑hour urine specimen is a probable indicator of a serotonin-producing tumor, offering high specificity when pharmacologic and dietary confounders are ruled out.
Special Instructions
Patient preparation includes avoidance of acetaminophen and tryptophan-containing supplements for 48 hours before and during collection. Limit fruits, vegetables, nuts, and caffeinated beverages/foods to one serving per day for 48 hours before and during collection. Use provided urine collection container with 25 mL of 50% acetic acid preservative (15 mL for children under 5 years) added at start of collection. Complete Oncology Test Request (T729) if not ordering electronically.
Limitations
Dietary intake of serotonin‑rich foods (e.g., fruits, nuts, tomatoes) and certain medications can falsely elevate or otherwise interfere with test results. All specimens are evaluated for suitability and improper collection or handling may compromise results. Interfering substances and inadequate collection may lead to misinterpretation.
New York Approved
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
LOINC Codes
- 13362-9
- 1695-6
- 3167-4
- 1695-6
Result Turnaround Time
2-4 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
5 mL
Minimum Volume
1 mL
Container
Plastic, 10‑mL urine tube
Collection Instructions
Collect a 24‑hour urine specimen. Add 25 mL of 50% acetic acid at start (15 mL for children <5 years).
Patient Preparation
Avoid acetaminophen, tryptophan supplements for 48 h; limit fruits, vegetables, nuts, caffeinated foods/beverages to one serving per day for 48 h.
Causes for Rejection
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 56 days |
| Frozen | 365 days |