5-Hydroxyindoleacetic Acid (HIAA), Quantitative, 24-Hour Urine
Also known as: 5-HIAA, Quantitative, 24-Hour Urine, Serotonin Metabolite, 24-Hour Urine
Use
This test measures urinary 5-hydroxyindoleacetic acid (5-HIAA), a principal metabolite of serotonin, which is useful in diagnosing and monitoring treatment of carcinoid syndrome, particularly related to serotonin-secreting neuroendocrine tumors. The presence of elevated 5-HIAA levels in the urine can indicate well-differentiated functional gastroenterohepatic neuroendocrine tumors, and correlate with carcinoid syndrome severity. Compared to those with normal levels, elevated urinary 5-HIAA levels are associated with a poorer prognosis and can reveal excessive conversion of tryptophan to serotonin.
Special Instructions
Record total 24-hour urine volume on the request form. Avoid bananas, avocados, plums, eggplant, tomatoes, plantain, pineapple, walnuts, and interfering drugs for a 72-hour period prior to and during collection. This includes aspirin, certain antidepressants, and various other drugs listed.
Limitations
5-HIAA levels may not rise in nonfunctional tumors, and interference can occur due to diet and medications. 5-HIAA levels are influenced by foods and drugs, with specific substances causing either elevation or reduction. In some conditions, large amounts of serotonin produced are not metabolized, necessitating blood serotonin level tests or repeated urine collections for accurate diagnosis.
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 1695-6
- 31203-3
- 1695-6
Result Turnaround Time
4-8 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
4 mL aliquot
Minimum Volume
1 mL aliquot
Container
Plastic urine container, no preservative
Collection Instructions
Void 8 AM and discard. Collect all urine including final specimen at 8 AM next day. Secure lid, label with patient's name, date, and time, and measure and record total urine volume. Send aliquot.
Patient Preparation
Avoid listed foods and medications for 72 hours prior and during collection.
Storage Instructions
Room temperature
Causes for Rejection
pH <2
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 14 days |
| Frozen | 14 days |