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Phenylketonuria In Children


Phenylketonuria (PKU) is a condition that prevents your child's body from breaking down phenylalanine. Phenylalanine is a substance the body uses to make other proteins that are needed for normal growth. Phenylalanine is found in many foods, such as meat, poultry, fish, eggs, milk, cheese, beans, nuts, and seeds. When phenylalanine is not broken down properly, it builds up in the body. It can cause brain damage and lead to serious growth and learning problems, such as mental retardation.


Follow up with your child's healthcare provider as directed:

Your child will need regular blood tests to check his phenylalanine levels. Write down your questions so you remember to ask them during your visits.


  • A special diet is needed to keep the amount of phenylalanine in your child's body low. It is started as early as the first few days of life or a few weeks after birth. Your baby will need to drink formulas that have little or no phenylalanine. These formulas have the right amino acids, calories, vitamins, and minerals your child needs. Ask your child's healthcare provider for more information about these formulas.
  • Your child will need to eat foods low in phenylalanine for the rest of his life. Phenylalanine is found mostly in foods that contain protein. The amount of protein your child can have depends on your child's phenylalanine levels, age, weight, and other factors. Your child's dietitian will plan and adjust the amount of protein your child is allowed to eat.

Contact your child's healthcare provider if:

  • Your child becomes more irritable and fussy than usual.
  • You have problems feeding your child.
  • You have questions or concerns about your child's condition or care.

Seek care immediately or call 911 if:

  • Your child cannot eat or drink.
  • Your child has a seizure.
  • Your child is vomiting everything he eats or drinks.

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The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.