The 24-hour urinary serotonin (5-HT) and 5-hydroxylndoleacetic acid (5-HIAA) outputs were repeatedly measured in 21 patients with major affective disorders after a minimum of three weeks free of drug treatments and at steady state during subsequent antidepressant treatments or during the second week after a series of electroconvulsive treatments (ECTs). The 5-HIAA outputs were more variable over time than the outputs of major catecholamine metabolites, previously studied by us. Patients with rapid mood cycles excreted large amounts of 5-HT. Lithium carbonate and ECTs reduced the outputs of 5-HT and 5-HIAA, respectively. Lithium carbonate also stabilized the output of 5-HT. No common effect of different antidepressant treatments on indole outputs was found.
Linnoila M, Miller TL, Bartko J, Potter WZ. Five Antidepressant Treatments in Depressed PatientsEffects on Urinary Serotonin and 5-Hydroxyindoleacetic Acid Output. Arch Gen Psychiatry. 1984;41(7):688-692. doi:10.1001/archpsyc.1984.01790180058007