A further contribution to the choice of the dose for L-tryptophan load test.

The analysis of the results of a study on the urinary excretion of metabolites "via kynurenine" after the ingestion in man of different amounts of tryptophan is reported. Of the three doses of L-tryptophan administered to the subjects, that is 2 g pro capite, 50 mg/Kg and 75 mg/Kg body weight, it is preferable to choose that of 50 mg/Kg b.w. as a load test. Such a dose assures an excretion of the more important metabolites without significant variations between men and women and without producing overloading effects.