Skip to main content

We use cookies to help us improve your experience and to provide services like web chat. We also use cookies to measure the effectiveness of public health campaigns and understand how people use the website.

To find out more about cookies and how we use them, please see our privacy policy.


For health information and advice, read our pages on coronavirus.

Phenylketonuria (PKU) - heel prick screening

About phenylketonuria

Phenylketonuria (PKU) is an inherited condition. It means that a baby's body cannot break down the amino acid phenylalanine, which is found in protein.

This is caused by a problem with a gene, which limits production of the enzyme needed to break down phenylalanine.

High levels of phenylalanine in a baby's body are harmful. If untreated, they can lead to intellectual or physical disability.

Babies born in Ireland with PKU

Around 1 in every 4,500 babies born in Ireland will have PKU or a milder form called hyperphenylalaninaemia.

If both parents carry the altered gene they have a 1 in 4 chance of having a baby with PKU.

How heel prick screening can help

If the heel prick suggests your baby may have PKU, they will be referred to a specialist.

Your baby will be put on a special low-protein diet.

When babies with PKU are diagnosed as newborns and started on treatment, they grow up healthy and well, once the diet is adhered to.

page last reviewed: 28/11/2018
next review due: 28/11/2021