Skip to Content
Home > Wellness > Health Library > Phenylketonuria (PKU)
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:
November 20, 2015
John Pope, MD - Pediatrics & Chuck Norlin, MD - Pediatrics
To learn more about Healthwise, visit Healthwise.org.
© 1995-2016 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
I Want To...
Our interactive Decision Points guide you through making key health decisions by combining medical information with your personal information.
You'll find Decision Points to help you answer questions about:
Get started learning more about your health!
Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.
Feeling under the weather?
Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.