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

What it is:
This test measures the amount of 5-hydroxyindoleacetic acid (5-HIAA), the main breakdown product of serotonin, in a 24-hour urine sample.

Uses

• Detect and monitor serotonin-secreting tumors (carcinoid tumors)

Symptoms That May Lead to the Test

• Flushing of the face and neck

• Severe diarrhea

• Wheezing or asthma-like symptoms

• Abdominal pain

Abnormal Results

• High levels:

  • Carcinoid tumors

  • Other serotonin-secreting tumors

• Low levels:

  • Usually not clinically significant

  • May be influenced by diet or medications

Risks

• No major risks.

• Requires dietary restrictions prior to testing to avoid false results.