Newborn Screening

Newborn Screening: What You Need To Know

Soon after your baby is born, he/she will be routinely screened for a series of health conditions. This is known as the heel prick test and SHARON McCLURE explains what it is and why it is carried out. 

The heel prick test (or the Guthrie test) is usually carried out within a week of your baby’s birth.

A special device is used to gently prick your baby’s heel to collect a small sample of his blood onto a screening card. The card will be sent to a laboratory for testing to identify babies who may have a range of rare but serious conditions.

Babies are routinely screened for six inherited conditions:

Congenital hypothyroidism (CH)
CH is a lack of the thyroid hormone and affects one in 3,500 infants, although only a small number of cases are inherited. Without treatment, CH can cause poor growth and irreversible neurological problems. It is usually treated with medication.

Phenylketonuria (PKU)
Around one in 4,000 children are born in Ireland every year with PKU. It is a metabolic disorder where sufferers have problems breaking down an amino acid called phenylalanine from the food they eat. If untreated, the build-up of phenylalanine in the brain can be toxic, resulting in brain damage. The condition is treated with a controlled diet and most children go on to lead a normal, healthy life.

Maple syrup urine disease (MSUD)
Approximately one in 125,000 babies will be born with MSUD. It gets its name from the fact the urine and earwax of sufferers can smell like maple syrup. Babies born with MSUD can’t break down certain amino acids, which results in a toxic build-up in the body. In its most severe form, MSUD can result in serious damage to the brain. However, the disease can also be controlled by diet and sufferers can go on to lead a normal, healthy life.

Classical galactosaemia
Sufferers of this condition have the inability to break down galactose (a sugar found in the lactose contained in human and cows’ milk). It affects one in 19,000 babies, however, this disease is common in the Traveller community where it is present in one in 40 babies. For this reason, babies born to Traveller parents are screened at birth and routinely offered a galactose-free milk soultion until test results are known. If this condition is left untreated, it can cause liver damage and may even be life threatening. Classical galactosaemia can also be controlled through a strict diet.

Cystic fibrosis (CF)
This condition affects the internal organs by clogging them with thick mucus. It mainly affects the lungs and digestive system, making it difficult for sufferers to breathe and to digest food. CF affects one in 1,500 babies and it is treated with medication and physiotherapy. Early detection of this disorder helps improve quality of life and can reduce time sufferers spend in the hopital.

This is an amino acid disorder where methionine is not broken down properly causing it, along with the amino acid homocystine, to build up in the blood. If gone untreated, Homocystinuria can affect the eyes, bones, heart, and blood vessels, and cause growth and learning delays in children.

The Test Results
The heel prick test results are usually known within a week but you will normally only be contacted directly if there is a problem. The conditions tested for are rare and for most babies, results will come back normal. Occasionally, further tests are needed but this isn’t always cause for concern and could simply mean not enough blood has been collected.

However, if your baby is found to be at risk of having one of these conditions, then he will be referred to a specialist unit where a team of professionals will work with you to diagnose and manage his condition. If you are concerned or have a family history of any of these disorders, then you should speak to your GP or midwife.

Disclaimer: This is a guide and not a substitute for medical advice. You should always consult a doctor for further information.

maternity & infant

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