[Determination of urinary xanthurenic acid after oral loading of L-tryptophan in 88 cases of photodermatosis]

Disturbances in the kynurenine pathway are present in pellagra and pellagroid syndromes. In 88 photodermatoses, the authors found increased urinary excretion of xanthurenic acid after oral load of tryptophan in a number of light-induced eruptions, i.e. benign summer photodermatosis (40%), polymorphous light eruptions (37%), and persistent light reactions (36%) as well as in patients with acute alcoholic intoxication. These biochemical abnormalities in the kynurenine pathway allow for a pathogenetic approach in some photodermatoses.