Professional
Technical
IVT
5-HIAA
Pronunciation: five H-I-double-A
Also written as: 5-HIAA — 5-Hydroxyindoleacetic acid
A urine metabolite of serotonin used as a biomarker for carcinoid syndrome diagnosis.
Full Definition
5-Hydroxyindoleacetic acid (5-HIAA) is the primary urinary metabolite of serotonin and serves as a key biomarker for diagnosing and monitoring carcinoid syndrome. Elevated 24-hour urinary 5-HIAA levels indicate excessive serotonin production by functional neuroendocrine tumors. The test requires dietary restrictions before collection, avoiding foods high in serotonin such as bananas, nuts, and certain medications. Levels correlate with disease burden and can be used to monitor treatment response.
Usage
Usage note: Include hyphen between 5 and HIAA in abbreviation.
In Context
- "Twenty-four-hour urinary 5-HIAA was markedly elevated at 180 mg (normal <6 mg)." — laboratory report
- "The patient was instructed to avoid bananas and nuts before 5-HIAA collection." — test preparation
Also known as
5-hydroxyindoleacetic acid
urinary 5-HIAA
Don't confuse with
5-HTP
5-HETE
serotonin level