The evaluation of phenylketonuria is performed at birth.

The physical exam is normal in an infant with phenylketonuria.

Testing for phenylketonuria is performed routinely on newborns.

Tests that are used to evaluate phenylketonuria include:

• Serum phenylalanine level

In high-risk pregnancies, the diagnosis of phenylketonuria can be made during amniocentesis, prior to birth.