Desert Storks

New Born Screening Test

The Newborn Screening Test, sometimes called a ‘Guthrie test’ or ‘heel prick’ test, is part of the normal care for newborn babies in Australia. This blood test is used to screen all newborn babies for some rare metabolic and congenital disorders. In Australia, advanced technology allows the testing from a single blood sample for over 30 different health problems.

These include congenital hypothyroidism, phenylketonuria (PKU), cystic fibrosis (CF), galactosaemia, and several conditions affecting the breakdown of fats (fatty acid oxidation defects) and proteins (amino acid metabolism disorders). Many of these conditions are genetic, and inherited from two healthy parents each carrying the abnormal gene.

Babies born with any of these health problems generally appear healthy and well at birth. Signs that something is wrong often cannot be recognised until the baby is several weeks or months old. Undiagnosed and untreated babies become seriously sick and may die. Early treatment greatly reduces, and often prevents, the effects of serious problems for the rest of the baby’s life. The objective of the screening program is to detect those babies whose tests suggest a high risk of any of these conditions. Follow up diagnostic testing will confirm whether the baby has the specific condition.

A trained midwife performs the Newborn Screening Test when the baby is about two days old (after 48hours). If mother and baby are discharged early, the mother and baby are asked to return to the hospital when the child is over 48hours old. For the test, a few drops of blood are taken from the baby’s heel and collected onto three small spots on a specially prepared absorbent paper card. The blood spots are allowed to dry and the card is sent to the Princess Margaret Hospital.

The results of the tests are sent back to the hospital within two weeks. If there is a suggestion that the baby may have a problem, the parents are notified immediately and arrangements are made for further tests to confirm or exclude the disorder. Parents are not notified of normal test results.

Each of these health problems are rare, but added together, they occur about 1 in every 800 babies.

Congenital hypothyroidism
The thyroid gland (in the neck) of babies with this condition does not produce enough thyroid hormone. An insufficient amount of this hormone slows brain development and growth. Early detection and treatment with thyroid hormone tablets allows children with this condition to grow and develop normally.

Phenylketonuria (PKU) and other amino acid metabolism disorders
PKU is the most common amino acid metabolism disorder where the baby cannot break down one of the amino acids (building blocks of proteins) called phenylalanine. This results in the build up of phenylalanine and other chemicals which cause brain damage if the baby is not treated. Feeding a special diet soon after birth allows these babies to develop normally. In addition to PKU the Neonatal Screening Test also detects other rare disorders of amino acid metabolism.

Cystic fibrosis (CF)
In CF the mucus produced in the intestine and lung is sticky and thicker than normal. Affected individuals are prone to serious chest infections and have difficulties in digesting food properly. The Newborn Screening Test for CF detects 96% of babies with it. Early diagnosis and treatment is important as recent medical advances have improved the life of children, although it does not prevent all the problems.

Galactosaemia
Babies with galactosaemia cannot break down one of the sugars (galactose) in milk and accumulate high levels of this sugar in blood. If untreated, this leads to severe health problems including cataracts, brain and liver damage or death. Feeding babies a special diet which does not contain galactose can prevent these health problems.

Fatty acid oxidation defects (FAOD)
Babies with a FAOD cannot use their stored fat to provide energy during a time of stress, causing the body to use all of its blood sugar for energy. This results in low blood sugar levels that can be fatal if not treated. Children with a FAOD are generally well unless they have a viral infection (cold or flu) or go for longer than usual between meals, when they may develop a severe problem. Treatment for this group of disorders involves careful monitoring of food intake and avoiding prolonged periods of fasting.