5-Hydroxyindoleacetic acid (5-HIAA) in urine

Why This Test Is Done

Your healthcare provider may order this test if you have symptoms like chronic diarrhea, abdominal pain, or unexplained weight loss. It’s also used to check for conditions such as carcinoid syndrome or other serotonin-related disorders, especially when other tests are inconclusive.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to collect a 24-hour urine sample. Follow your provider’s instructions carefully to ensure accurate results. Avoid certain medications or foods that could interfere with the test results.

What the Test Involves

You will collect urine over a 24-hour period, typically starting after waking up in the morning and continuing until the next morning. The sample is then sent to a lab for analysis.

What the Results Mean

Higher than expected levels of 5-HIAA may suggest conditions like carcinoid syndrome or other serotonin-producing tumors. Lower levels could indicate malabsorption issues or other gastrointestinal disorders. Your results will be interpreted by your healthcare provider in the context of your symptoms and medical history.