Xanthurenic Acid Excretion Studies in Diabetics With and Without Retinopathy.

Abstract
The status of diabetics, subdivided on grounds of ophthalmological diagnosis into the presence or absence of retinopathy, with regard to pyridoxine was determined by analyzing 24 hour urines for xanthurenic acid after an oral test-load of dl-tryptophane. When the xanthurenic acid excretion level of diabetics was compared with normal controls, diabetics were found to excrete significantly higher amounts of this abnormal metabolite. No statistically significant difference was found between the 2 diabetic groups. The abnormal excretion of xanthurenic acid was reversible with pyridoxine. It is therefore concluded that diabetics with and without retinopathy are vitamin Bg deficient.