Alternate Names : PKU, Phenylalanine Hydroxylase Deficiency
How is the disease diagnosed?
Phenylketonuria is diagnosed when high levels of phenylalanine are found in
the blood. Testing for PKU is generally done with a screening blood test
within 48 hours of birth. Babies who test positive on the initial screening
test will be evaluated again with a more specific test for PKU.
Phenylalanine levels may be normal at birth but go up once the baby is fed. It is important to
evaluate babies after they have received dietary protein for 24 to 48 hours.
The practice of discharging babies from the hospital within 24 hours of
delivery has resulted in failure to detect some infants with PKU.