The 5-hydroxyindoleacetic acid (5-HIAA) test is used to help diagnose and monitor carcinoid tumors. It can be ordered alone or together with a serotonin and / or chromogranin A blood level. This test is ordered primarily when you have signs and symptoms that suggest a carcinoid tumor.
Why get tested ?
To help diagnose and monitor treatment for a serotonin-producing carcinoid tumor.
When to get tested ?
When you have symptoms that suggest a carcinoid tumor, such as redness, abdominal pain, diarrhea and / or wheezing; at intervals after treatment
- Serotonin (5-Hydroxytryptamine) produced by Carcinoid
- Serotonin converted to 5-HIAA for excretion
- Normal: Urine 5-HIAA < 9 mg/day
- Equivocal: Urine 5-HIAA 9 to 25 mg/day
- Possibly consistent with Carcinoid Syndrome
- See Other causes of 5-HIAA elevation
- High: Urine 5-HIAA >25 mg/day
- Diagnostic for Carcinoid Syndrome
Increased Urine 5-HIAA 24 hour Levels
- Malignant Carcinoid (>25 mg/day)
- Acute Intestinal Obstruction
- Celiac Sprue
- Excessive Banana or walnut ingestion