How can i diagnose phenylketonuria from lab results?

Newborns screened: All states require PKU screening be performed on all newborns prior to discharge from the hospital. If the screening test is positive, the family and physician is notified immediately for confirmation testing. In the event an infant was not tested, as in home birthing, symptoms of untreated PKU would likely prompt a doctor visit, where a simple blood test could be performed.