What is the reason for pKU?

SHERRY 2022-03-24


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Phenylketonuria (also known as pKU) is a disease of an amino acid that the body cannot break down, called phenylalanine. Amino acids help build proteins in the body. If left untreated, phenylalanine can build up in the blood and cause health problems.

What is the reason for pKU?

pKU is inherited. This means that it is passed from parent to child through genes. Genes are the part of your body's cells that store instructions for how your body grows and works. Genes come in pairs - you get one from each parent.

Sometimes the instructions in the genes change. This is called a genetic change or mutation. Parents can pass genetic changes on to their children. Sometimes genetic changes can cause genes to not work properly. Sometimes it can lead to birth defects or other health conditions. A birth defect is a health condition when a baby is born.

Your baby must inherit a genetic change from both parents to pKU in order to develop pKU. If they only inherit genes from their parents, they have a genetic change in pKU, but they don't have pKU. When this happens, your baby is called a pKU carrier.

How do I know if my baby has pKU?

All babies are screened for pKU shortly after birth. Early detection of pKU can help doctors treat it so that the baby can grow up healthy.

Before your baby leaves the hospital, their healthcare provider will take a few drops of blood from their heels. Blood is collected on a special piece of paper and sent to a lab for testing. If the newborn screening results are not normal, it means your baby needs more tests. Your baby can recommend another test, called a diagnostic test. Tests can check to see if your baby has pKU, or if there are other reasons for the abnormal test results.

If your baby is tested before they are all day old, you may miss a pKU. Some experts recommend that if your baby is tested within 24 hours of birth, you should be tested again at 1 to 2 weeks old.

What problems can pKU cause?

pKU babies look normal for the first few months of life. But if left untreated, they can start showing signs and symptoms of the disease at about 6 months of age. These include:

Astringent movements of the arms and legs.

Body pigments for light skin and eye skin and hair color.

Moldy body odor.



Small head size

Sitting, crawling or walking took longer than expected.

Losing interest in surroundings.

Delayed mental and social skills.

Intellectual disability

Behavioral problems such as hyperactivity.

If your baby has pKU, what kind of treatment will they need?

If your baby has pKU, they may need to check their phenylalanine levels once a week or more frequently. After that, they can be tested once or twice a month throughout childhood.

Your baby needs to follow a special diet plan that is low in phenylalanine. It's best to start this diet plan as soon as possible, preferably on the diet plan of life.

In the beginning, your baby will get a special protein formula to reduce phenylalanine. Protein is very important in helping babies grow and develop. Control the content of phenylalanine in the formula to meet the individual needs of infants. Your baby can also drink some breast milk/breast milk. Breast milk contains phenylalanine, so check with your baby's supplier to find out how much your baby can eat.

When your baby prepares solid foods, they can eat vegetables, fruits, grains (such as low-protein cereals, bread, and pasta), and other foods that are low in phenylalanine. If your baby has pKU, they shouldn't eat:

Dairy products such as milk, cheese, ice cream, etc.


Meat and poultry


Nuts, seeds, oats, rye, barley, gelatin.


Contain aspartame or beverages. This is an artificial sweetener that contains a lot of phenylalanine. It is sold as Nutraswet and Equal.

Each baby's pKU meal plan is different and will change over time, depending on how much phenylalanine your baby can tolerate. A healthcare provider at the pKU medical center or clinic can help you create a meal pku diet for your baby. For information on pKU medical centers or clinics, please consult your heart or clinic.

Your child will follow the Peking University diet plan for life. If they end up pregnant, they will follow their diet plan. Most pKU pregnant women and parents have healthy pregnancies and healthy babies.

The drug Kuvan (sapropterin dihydrochloride) can help some people with pKU. This drug is more likely to work in people with mild or specific forms of pKU. Children taking Kuvan must follow a special diet plan, but may not be as strict for children who are not taking the medicine. They still need regular blood tests to check phenylalanine levels.