[The activity of glutathione-reductase and FAD-effect as indicators of the riboflavin level in experiments and in patients with phenylketonuria].

Subjects of discussion in the paper are various methods of determining the riboflavin allowances and the results achieved by the application of two of them that concern determining the activity of the glutathione-reductase and the FAD-effect in the study of an experimental B2-deficiency in rats and the riboflavin allowances in children suffering from phenylketonuria. Exclusion of vitamin B2 from the ration of rats resulted in that in 8 weeks they developed B2-deficiency ascertained with the help of the above cited enzymatic tests. In a certain percentage of children with phenylketonuria after discontinued administration of group "B" vitamins (D1 diet) there could be observed an intensification of the FAD-effect and, accordingly, a reduced glutathione-reductase activity. Resumed taking of the vitamins (D2 diet) normalized the riboflavin allowance values in at least, one week's time.