Primary early onset dysthymia, biochemical correlates of the therapeutic response to fluoxetine: II. Urinary metabolites of serotonin, norepinephrine, epinephrine and melatonin

The present study investigated pre- and post-treatment 24-h urinary metabolites of monoamines and melatonin as a function of response to treatment in primary early onset dysthymic patients. The main finding was that treatment responders had lower urinary 5-hydroxyindoleacetic acid (5-HIAA) levels prior to treatment. Following treatment, urinary 5-HIAA tended to be decreased in nonresponders and increased in responders. As well, metanephrine levels were lower and 6-sulphatoxymelatonin levels were higher in responders prior to treatment. These data support the view that there is a biological substrate for certain subgroups of dysthymia, part of which may involve serotonergic systems.