About this test
This quantitative test measures 5-hydroxyindoleacetic acid (5-HIAA) in a 24-hour urine collection. 5-HIAA is the main breakdown product of serotonin, a hormone and neurotransmitter. Elevated levels can indicate the presence of serotonin-producing tumors, most commonly carcinoid tumors. It is crucial for diagnosis, staging, and monitoring treatment effectiveness in individuals suspected of or diagnosed with carcinoid syndrome.