Phenylketonuria (PKU) is an inherited disorder in which the body cannot break down an amino acid called phenylalanine, which is a part of protein. If treatment is not started soon after birth, phenylalanine levels rise and can cause lasting brain and nervous system damage, such as intellectual disability.
Symptoms of PKU usually appear within a few months of birth, after phenylalanine has built up in a baby's blood. Before birth, the mother's body filters out the excess phenylalanine for the baby (fetus).
Early symptoms may include:
Screening for PKU is routinely done shortly after birth, making early diagnosis and treatment possible.
People with PKU must follow a diet low in protein throughout life. Women of childbearing age with PKU must carefully manage their phenylalanine levels to prevent harm to their baby should they become pregnant. Babies born to mothers who have high phenylalanine levels during pregnancy are at risk for intellectual disability and other developmental problems.
Current as of: August 21, 2015
Author: Healthwise Staff
Medical Review: John Pope, MD - Pediatrics & Chuck Norlin, MD - Pediatrics
To learn more about Healthwise, visit Healthwise.org
© 1995-2015 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
Donations to UW Health are managed by the University of Wisconsin Foundation, a publicly supported charitable organization under 501(c)(3) of the Internal Revenue Code.