Phenylketonuria (PKU)



What is phenylketonuria?

Phenylketonuria, also called PKU, is a genetic disorder where your body is unable to break down an amino acid called phenylalanine. An enzyme in your body called phenylalanine hydroxylase can process phenylalanine into tyrosine to create neurotransmitters, such as epinephrine, norepinephrine, and dopamine.

Because of this genetic defect, phenylalanine will build up in your body easily while there is not enough tyrosine to form new cells. This can lead to some serious health complications.

People with PKU need to follow a strict diet with limited amount of protein. The phenylalanine in your body comes from protein in your diet, particularly high-protein foods, such as: meat, fish, eggs, cheese, and milk.

How common is phenylketonuria?

This health condition is rare. It is an inherited disorder, which means the baby is born with the disorder. Please discuss with your doctor for further information.


What are the symptoms of phenylketonuria?

Phenylalanine plays a role in the body’s production of melanin, the pigment responsible for skin and hair color. Therefore, infants with the condition often have lighter skin, hair, and eyes than brothers or sisters without the disease.

Tyrosine – another product of phenylalanine processing – is used to make neurotransmitters, lack of this amino acid can lead to damage to the brain and nervous system:

  • Depression ;
  • Anxiety disorder;
  • Phobias
  • Low self-esteem

Untreated, it can lead to serious complications in children:

  • Irreversible brain damage and intellectual disabilities within the first few months of life;
  • Behavioral problems and seizures in older children.

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

You should contact your doctor if you have any of the following:

  • If you are a women who plans to have a child, get a genetic check before having a child is recommended.
  • If your new born baby has PKU, your doctor will start a low-protein diet to prevent long-term harm.
  • Adults with PKU continue to receive life-time health care

If you have any signs or symptoms listed above or have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.


What causes phenylketonuria?

Phenylketonuria is a genetic condition in which the PAH gene that responsible for creating phenylalanine hydroxylase is abnormal.

It is possible that the parents have the defect in their gene but no symptoms. Therefore, PKU is passed to children by two parents who are carriers of the disorder, but don’t know it.

Risk factors

What increases my risk for phenylketonuria?

There are many risk factors for phenylketonuria, such as:

  • Having two parents with a defective PKU gene. Both parents must pass along a copy of the mutated PKU gene for their child to develop the condition.
  • Being of certain ethnic decent. The gene defect varies by ethnic groups and is less common in African-Americans than in other ethnic groups.

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is phenylketonuria diagnosed?

Phenylketonuria can be identified by a simple blood test at birth of a child. This test will also tell if there are any other medical conditions you should be worry about. If the screening test is positive, further blood and urine tests as well as genetic test are required to confirm the diagnosis.

Adults with PKU will also need to take blood test once in a while to measure their blood phenylalanine level.

How is phenylketonuria treated?

Treatment starts as soon as you are diagnosed with this condition. In most cases, it is start at birth. The doctor will advise the parents of foods they should avoid giving the child. The main treatment for PKU is a low-protein diet that completely avoids high-protein foods – such as meat, eggs and dairy products – and controls the intake of many other foods, such as potatoes and cereals. This diet will continue with the child into adulthood. You might also need to give your child amino acid supplements to ensure your health.

In adults, the same diet is applied, although they are more tolerant of eating high-protein food. As a result, some may find that they don’t function as well – for example, they may lose concentration or have a slower reaction time. Others don’t seem to have any problems and lead a normal life. In pregnant women, a strict low-protein diet is recommended to avoid complication for the fetus.

There are several special formulas made for infants with PKU. These can be used as a protein source that is extremely low in phenylalanine and balanced for the remaining essential amino acids.

Lifestyle changes & Home remedies

What are some lifestyle changes or home remedies that can help me manage phenylketonuria?

The following lifestyles and home remedies might help you cope with phenylketonuria:

  • Getting a genetic testing before having a child;
  • Pick the low-protein version of foods. There are many brands that sell low-protein flour, for example;
  • Keep track of your protein intake;
  • Try out low-protein recipes;
  • Plan ahead when you eat out;
  • Educate yourself and your friends and family on your condition.

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: July 17, 2017 | Last Modified: July 18, 2017

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