[24 hours plasma tryptophan levels in patients with endogenous depression (author's transl)]

The variations of total and free tryptophan during 24 hours were measured in patients with endogenous depression. In depressive patients, plasma tryptophan levels are significantly lower than in control subjects. Plasma tryptophan levels in depressive patients are low during the night (when high at the same hours in normal subjects). The physiopathological mechanisms of such alterations and their possible influence on symptomathology are described.