5‑Hydroxyindoleacetic Acid (5‑HIAA), 24‑Hour Urine without Creatinine

Clinical Use

Use

This test measures the 24‑hour excretion of 5‑hydroxyindoleacetic acid (5‑HIAA), a serotonin metabolite, useful for the biochemical diagnosis and monitoring of carcinoid syndrome and related conditions. Elevated 5‑HIAA levels may indicate increased serotonin production, which is characteristic of carcinoid tumors.

Special Instructions

Not provided.

Limitations

Specimen rejection occurs if urine pH exceeds 3.0 when received unfrozen. Urine without preservative is acceptable only if pH is below 6 and the sample is shipped frozen. Improper diet or medication use may result in falsely elevated levels.

Test Details

Methodology

Other

Biomarkers

5‑Hydroxyindoleacetate

Analyte

Quantitation

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

Total Volume

Analyte

Quantitation

Concentration / Level • Quantitative (Continuous) (e.g., copies/mL, % expression)

LOINC Codes

Order Codes

1695-6 - 5OH-indoleacetate 24h Ur-mRate
3167-4 - Specimen vol 24h Ur

Result Turnaround Time

2 days

Specimen

Urine

Volume

10 mL (5 mL minimum)

Minimum Volume

Not provided

Container

24‑hour urine container

Collection Instructions

Collect 24‑hour urine in container with 25 mL of 6 N HCl to maintain pH < 3. If preservative not used and pH ≤ 6, specimen must be shipped frozen. Keep refrigerated during collection if unpreserved. Record 24‑hour volume and patient age on container and requisition.

Patient Preparation

Avoid foods high in indoles (avocado, banana, tomato, plum, walnut, pineapple, eggplant) and avoid tobacco, tea, and coffee prior to and during collection.