A simple heel prick test

Dr Elizabeth
3 min readJul 11, 2022

As the time get near to the birth we are naturally excited. Looking forward to that healthy bouncing baby. Whether it is a planned labour an unexpected delivery the nursing staff do all in their power to assist. Afterwards baby gets all the appropriate checks including one that many most people never give much thought to. And that is a simple heel prick test. For most parents they will let the professionals do their work and not give a thought to why the needle is going in the little one’s foot. And at such a happy time why should they?

With this in mind this test was brought into a national screening program in the UK’s NHS in 1969. A simple heel prick test using Guthrie’s blood spot test. The test is used to diagnose a rare metabolic disorder. This condition is known as Phenylketonuria (PKU). In order to get a positive result they will have inherited 2 faulty copies of the gene for PKU one from each parent. Although there are over 300 different mutations the risk is the same for both males and females. .

Positive Heel prick test — what now?

The blood test that is taken from the heel prick test , parents receive the result in a couple of days. If it comes back positive for PKU. The words can be so devastating for parents. Anyone that has PKU cannot metabolise phenylalanine, an amino acid found in protein foods. Medical staff do everything they can to support baby and parents. Consequently offer support and advice and answer all questions. Advice will be given and hospital follow up appointments arranged. In the UK one in 10,000 babies are born with this rare disease.

This metabolic condition prevents the baby from being able to break down protein and immediately their diet needs to be changed. Until the baby is on solids they will get changed to a phenylalanine-free formula. People with PKU and their families spend approximately 19 hours per week managing their very restrictive complex diet. With this in mind sorting out, weighing food is vital, cutting out certain foods is essential.


Dr Elizabeth

Medical writer & editor. Love, my family, my labradors & life itself. Passionate writer, photographer. Health blogger. Phd Health Economics.