5-HIAA measurement

quantification of 5-hydroxyindoleacetic acid in cerebrospinal fluid or urine. 5-HIAA is a metabolite of serotonin.n This measurement is performed during diagnosis of serotonin secreting neuroendocrine tumours.nLow levels of 5-HIAA in the cerebrospinal fluid have been associated with aggressive behavior and suicide by violent means, correlating with diminished serotonin levels.nElevated serotonin (hyperserotonemia) is one of the most common biological findings in autism[3] and 5-HIAA may be elevated in patients with autistic spectrum disorders.