5‑Hydroxyindoleacetic Acid (5‑HIAA), 24‑Hour Urine without Creatinine
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
Patients should avoid foods high in indoles—including avocado, banana, tomato, plum, walnut, pineapple, eggplant—and tobacco, tea, and coffee for 48–72 hours before and during collection. Record patient age and total 24‑hour urine volume on both the collection container and test requisition.
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.
Methodology
Other
Biomarkers
LOINC Codes
- 1695-6
- 3167-4
Result Turnaround Time
2 days
Related Documents
For more information, please review the documents below
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.
Causes for Rejection
pH > 3.0 and received unfrozen
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 30 days |
| Frozen | 30 days |