Excretion of tryptophan metabolites in different forms of haemoblastosis

Abstract

Spontaneous excretion of tryptophan metabolites was followed in 68 patients affected by haemoblastosis. Abnormal levels of kynurenine were found to be excreted by 8 out of 13 subjects with malignant lymphoma, by 8 out of 22 subjects with leukaemia, and by 3 out of 5 cases with multiple myeloma. In all 28 Hodgkin's disease patients examined, kynurenine was excreted consistently above normal levels. Excretion values varied among the patients and were roughly correlated to the severity of the disease. Abnormal amounts of 3-hydroxy-kynurenine and 3-hydroxyanthranilic acid were excreted by a few of the same patients. Administration of vitamin B 6, as pyridoxine hydrochloride or pyridoxal-5-phosphate, In io patients with Hodgkin's disease normalized kynurenine and 3-hydroxykynure-nine excretion whereas it caused a contemporaneous increase of urinary 3-hydroxy-anthranilic acid. The effects of several therapeutic agents on the excretion were also observed. Tryptophan loading tests (50 mg/kg) were performed in n Hodgkin's disease patients: excretion of kynurenine, N-α-acetyl-kynurenine, 3-hydroxykynurenine, kynurenic, xanthurenic, and 3-hydroxyanthranilic acids was determined in comparison with that of 5 normal controls. The total amount of these substances was 3.3 times larger in these patients than in the controls. A week after the first load a second tryptophan test was carried out with contemporaneous administration of 3 large doses of vitamin B 6. Pyridoxine was unable to normalise the patients' excretion. The vitamin acted by increasing the amount of 3-hydroxyanthranilic acid and by decreasing the amounts of the other metabolites.