PKU displays a marked genotypic heterogeneity, both within populations and between different populations. Perform screening on blood samples during the first week of life. Perform urinalysis of biopterin and neoptrins to exclude defects of biopterin synthesis or recycling. Wide variability in phenylalanine concentrations in a 24-hour period in children with PKU may require repeat screening. Perform cranial MR spectroscopy to determine brain metabolite concentrations and brain compartmentation.
Prenatal diagnosis is experimental.
Prenatal diagnosis can be made in families at risk with the help of a combination of DNA analysis, enzyme activity, and amniotic fluid metabolite levels. Diet should not be terminated after adolescence because strong indications exist that hyperphenylalaninemia can have detrimental effects in adult patients. As a result of the lack of internationally accepted guidelines, management of PKU varies among countries. Supplement diet with tyrosine. Aspartame is used widely in medicines, vitamins, beverages, and many other products.