5-HIAA Unit Converter

5-Hydroxyindoleacetic acid (5-HIAA) is the main breakdown product of serotonin, a chemical messenger involved in mood, sleep, appetite, and gut function.

After serotonin performs its functions in the body, it is broken down by the enzyme monoamine oxidase (MAO), primarily in the liver. The resulting 5-HIAA is then excreted in the urine.

Measuring 5-HIAA in urine serves as an indirect way to assess how much serotonin your body is producing and metabolizing. This test is most commonly used to detect and monitor carcinoid tumors, which are neuroendocrine tumors that often produce excessive amounts of serotonin.

5-HIAA is produced when serotonin is broken down by the enzyme monoamine oxidase (MAO), mainly in the liver. Serotonin itself is primarily made by enterochromaffin cells in the gastrointestinal tract (about 90%), with smaller amounts produced in the brain and other tissues.