Phenylketonuria - Diagnosing phenylketonuria
- Introduction
- Symptoms of phenylketonuria
- Causes of phenylketonuria
- Diagnosing phenylketonuria
- Treating phenylketonuria
Phenylketonuria (PKU) is diagnosed in newborn babies after a routine blood test.
Newborn screening
All newborn babies are routinely screened for PKU using a blood test that's usually carried out about a week after birth.
A sample of your baby’s blood will be taken using a blood spot or heel prick test (sometimes known as a Guthrie test) and sent to a laboratory, where phenylalanine levels will be measured. If levels are unusually high, a second blood sample will be taken to confirm the diagnosis.
If the second test confirms high phenylalanine levels, your baby will be referred to a doctor who specialises in treating PKU. You'll also be referred to a dietician, who will advise you about changes that need to be made to your baby’s diet.
Read more about treating phenylketonuria.
Regular blood tests
If a diagnosis of PKU is confirmed, your child will need regular blood tests to measure levels of phenylalanine in their blood and assess how well they're responding to treatment. Only a drop of blood is needed, and it can be collected at home and sent to the hospital by post.
It's recommended that children who are:
- six months of age or younger should have their blood tested once a week
- between six months and four years of age should have their blood tested once every two weeks
- over four years of age (and all adults) should have their blood tested once a month
Someone with PKU will usually need to have regular blood tests throughout their life.
You may be able to have training so that you can carry out your child’s blood tests, or be able to test yourself if you have PKU. This will make testing more convenient.
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