Phenylketonuria In Children


  • Phenylketonuria (fen-il-ke-to-NU-re-ah) is also called PKU. This is an inherited condition where the body cannot break down certain foods properly. With PKU, there is an error with the enzyme that is needed to break down phenylalanine. This enzyme may be present only in small amounts or none at all. Phenylalanine may build up in the body and cause brain damage. Without treatment, signs and symptoms of PKU may appear within a few months. These can be mild or severe and may include problems with learning, speech, or behavior. Other symptoms include vomiting (throwing up), seizures (convulsions), rash, or a musty odor to the breath, hair, or urine.

  • A newborn screening test is usually done a day or two after your baby's birth. His blood is checked for PKU and other genetic disorders. Urine tests, computerized tomography (CT) scan, or magnetic resonance imaging (MRI) may also help diagnose PKU. A special diet is needed to help keep his phenylalanine levels low. Medicines and special formulas may also be given to control your child's symptoms and help with his nutrition. Many children who follow a strict PKU diet grow up to be normal, healthy adults. With treatment, such as medicines and proper diet, your child may grow normally and serious health problems may be prevented.



  • Keep a current list of your child's medicines: Include the amounts, and when, how, and why they are taken. Bring the list and the medicines in their containers to follow-up visits. Carry your child's medicine list with you in case of an emergency. Throw away old medicine lists. Give vitamins, herbs, or food supplements only as directed.

  • Give your child's medicine as directed: Call your child's healthcare provider if you think the medicine is not working as expected. Tell him if your child is allergic to any medicine. Ask before you change or stop giving your child his medicines.

Ask for more information about where and when to take your child for follow-up visits:

For continuing care, treatments, or home services for your child, ask for information.


Your child needs a special diet to keep his phenylalanine levels low. This diet is different from one child to another. A caregiver, called a dietitian, may talk to you about your child's feeding and nutrition. He will plan and make a list of foods that your child may take. He may also adjust the amount of proteins your child needs depending on his blood tests and follow-ups.

  • Avoid giving foods that are high in proteins: These include meat, poultry, fish, eggs, milk, cheese, beans, nuts, and seeds. Your child may need to stick with a low protein diet for life.

  • Follow the diet your child's caregiver gives you for your child: Your child should eat only the exact amount of each food listed on the diet. Use weighing scales or measuring cups or spoons when preparing your child's food.

  • Use additional special formulas or products: These may add extra calories, vitamins, and minerals to help him grow. Ask your child's dietitian for more information about these special formulas and products.

  • Use special cookbooks: This may help the cook in the family find new recipes. Ask your child's caregiver for more information about a low protein diet.

Journal or diary:

A journal or diary of information about your child's PKU may help him control his disorder. Write down the results of all his laboratory tests, especially the amount of phenylalanine. Record the food and drinks he has been eating or drinking. Write down any illnesses your child has or medicines he has been taking.

Working with your child:

  • Be patient and keep up hope for improvement: Your child, like every child, has a lifetime to learn and grow. Treat your son or daughter as you would treat a child without a disorder. Working together as a family and giving each other support will help during difficult times.

  • Keep informed about new treatments and technologies that may help: New approaches and therapies to help those with PKU are always being developed. Some may make a huge difference to the quality of your child's life. Talk to your child's caregiver before trying any new therapy or diet.

  • Learn about PKU: The more you know about PKU, the more you will be better able to help yourself and your child.


  • Your child cannot make it to the next meeting with his caregiver.

  • Your child becomes more irritable and fussy than usual.

  • You have problems helping your child with his diet.

  • You have questions or concerns about your child's disorder, treatment, or care.


  • Your child is not able to eat or drink.

  • Your child is having seizures (convulsions).

  • Your child is vomiting (throwing up) 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.

Learn more about Phenylketonuria In Children (Discharge Care)