MedicalTerminology DB
General Medical Terms

5-hydroxyindoleacetic acid

Meaning of 5-hydroxyindoleacetic acid: 5HIAA.

Definition of 5-hydroxyindoleacetic acid

5HIAA. A breakdown product of serotonin that is excreted in the urine. Serotonin is a hormone found at high levels in many body tissues. Serotonin and 5HIAA are produced in excess amounts by carcinoid tumors, and levels of these substances may be measured in the urine to test for carcinoid tumors.

Written and maintained by James Murray Last updated July 21, 2026 Educational reference, not medical advice. Read the limitations.

For learning, not diagnosis. This glossary provides general educational information and is not a substitute for advice from a qualified healthcare professional. If you may be experiencing a medical emergency, contact local emergency services.