Increased urinary excretion of some of themetabolites of the tryptophan-niacin pathway, with or without prior tryp

The 24-hr urinary excretion of certain metabolites of tryptophan was measured in 22 patients with Hodgkin's disease and 18 patients with lymphosarcoma, following the P.O. administration of 2 g L-tryptophan. An assay of hepatic tryptophan pyrrolase activity was done on 15 patients with Hodgkin's disease and 15 patients with lymphosarcoma, and an assay of hepatic ky'hureninase was done on 11 and 7 patients with Hodgkin's disease and lymphosarcoma, re spectively. There was increased urinary excretion of kynure nine in 9, of3-hydroxykynurenine in 16, ofkynurenic acid in 4, of xanthurenic acid in 4, and of acetylkynurenine in 3 patients with Hodgkin's disease. Similarly, there was an increase in urinary excretion of kynurenine in 5 , 3-hydroxy kynurenine in 7, kynurenic acid in 1, xanthurenic acid in 1, and acetylkynurenine in 5 patients with lymphosarcoma. The increased urinary tryptophan metabolite excretion was more common and more marked in patients with Stage III and IV Hodgkin's disease, particularly the symptomatic Group B patients. However, this correlation could not be made in the patients with lymphosarcoma because of the limited number of patients with Stage I and II disease. There was no correlation between tryptophan pyrrolase activity and either the level of urinary excretion of trypto phan metabolites or the stage of the disease. On the other hand, patients with low hepatic kynureninase activity tended to excrete increased quantities of these tryptophan metabo bites. Depressed kynureninase activity and increased excre tion of tryptophan metabolites were more marked in advanced Stage III and IV Hodgkin's disease.