Improved diagnosis of classical vs atypical phenylketonuria by liquid chromatography.

Atypical phenylketonuria among infants with hyperphenylalaninemia must be promptly diagnosed and differentiated from classical phenylketonuria, because these patients require different treatment to prevent irreversible neurological damage. Measurement of pteridines in urine by liquid chromatography has been widely used for this purpose. Here we report a rapid, simplified liquid-chromatographic method for simultaneously measuring urinary biopterin, neopterin, and creatinine. Unlike previous methods, this method involves neither tedious cleanup procedures nor special equipment.