5-Hydroxyindoleacetic Acid (HIAA), Quantitative, 24-Hour Urine

Also known as: 5-HIAA, Quantitative, 24-Hour Urine, Serotonin Metabolite, 24-Hour Urine

Clinical Use

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

Not provided.

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.

Test Details

Methodology

Mass Spectrometry

Biomarkers

LOINC Codes

Order Codes

1695-6 - 5OH-indoleacetate 24h Ur-mRate

Result Codes

31203-3 - 5OH-indoleacetate 24h Ur-mCnc
1695-6 - 5OH-indoleacetate 24h Ur-mRate

Result Turnaround Time

4-8 days

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.