[Phenylalanine metabolites in the urine after oral phenylalanine loading. Significance for the discrimination between classical phenylketonuria and variations of hyperphenylalaninemia (heterozygotes and homozygotes)].

Modern newborn mass screening for inborn errors of metabolism results in detection of newborns with hyperphenylalaninemia. This investigation demonstrates that gaschromatographic analysis of phenylalanine metabolites in urine after phenylalanine challenge is a useful method for discriminating between classical phenylketonuria and hyperphenylalaninemic variants.