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Certain diseases can be present at birth. However, early detection and treatment can help prevent potentially permanent mental retardation from rare disorders. Babies with certain disorders look normal at birth. That is why the blood test is so important, as well as a careful examination by a doctor or midwife. This early detection process is called newborn screening.
In their first week of life, all babies in B.C. are offered a simple blood test. Just before the baby is discharged from hospital, a small blood sample is taken by a simple heel prick. It will only cause a moment of discomfort. This sample is sent to the newborn screening lab for analysis.
The four disorders that newborns are tested for are:
PKU is a rare condition. It is found in about one out of every 18,000 new babies. A baby with PKU doesn't have enough of a special enzyme that breaks down phenylalanine in the body.
Phenylalanine is an amino acid - one of the building blocks of proteins. It is found in foods such as meat, eggs, fish and milk, including breast milk.
A shortage of this enzyme leads to high levels of phenylalanine in the blood. High levels of phenylalanine cause damage to the baby's brain. This usually leads to severe and irreversible mental retardation.
Those very few babies found to have PKU are put on a special diet low in phenylalanine. This prevents brain damage. Children with PKU, when treated early, function within the broad normal range of ability.
CH is more common than PKU - about one in 3,000 to 4,000 new babies are affected. Like PKU, CH is easily detected by the blood screening test.
Congenital means the baby was born with the condition. Hypothyroidism means that the thyroid gland (found behind the "Adams apple" in the neck) is not working properly and not producing enough thyroxine. This is a hormone that is needed for normal growth and development. If CH is not detected and treated early in life, severe mental retardation will occur. The treatment for CH is simple and effective. Babies are given thyroxine to replace the missing thyroid hormone, helping them to grow and develop normally.
GS is a rare condition found in only one out of every 30,000 babies born in B.C. A baby not having the special enzyme that breaks down galactose causes the condition. Galactose is found in milk, including breast milk, and in most infant formulas. If the baby doesn't have this enzyme to break down galactose, it starts to build up in the body.
Symptoms of this disorder include a general failure to thrive, liver problems (jaundice), cataracts, mental retardation and possibly even infection that can cause death. Early detection is critical. A baby is treated with a galactose-free diet.
MCAD is a rare condition. One baby in 20,000 is born with MCAD deficiency. A baby with this condition may have problems using fats stored in their body as an energy source. These babies do fine when they are eating well, but when they get colds and flus, they may not be able to use stored fats for energy. There is a risk of sudden unexpected death, which can be prevented by using a special diet and avoiding fasting.
The newborn screening test should be done between 24 and 48 hours after birth. The test is usually done before the baby leaves the hospital. Babies should not leave the hospital without a blood test.
The screening tests for Congenital Hypothyroidism (CH) and Galactosemia (GS) are reliable any time after birth. However, tests for Phenylketonuria (PKU) and Medium Chain Acyl-CoA Dehydrogenase Deficiency (MCAD) are not as reliable when done less than 24 hours after birth. Therefore, babies who are born in a hospital and stay longer than one day will be offered the test before discharge.
Babies born in hospital but discharged within a few hours of a delivery will either return to hospital for testing or have the test done during a home visit within the first week. Babies born outside a hospital setting (e.g. at home) under the care of a midwife will be offered the test during a home visit.
You should discuss these options with your physician, midwife or public health nurse to ensure that the test is done.
The results are usually ready in a few days. You will not be contacted if the results are normal (negative). If one of the screening test results is positive, your family doctor or midwife will contact you and additional testing will be arranged. The results of follow-up tests will either be normal (ruling out the possibility of one of these disorders) or will confirm the diagnosis.
Almost all test results are negative.
However, if your baby is one of the very few found to have one of these conditions, the early detection of the disorder will help your baby get effective treatment as soon as possible. The earlier these treatable disorders are found, the better the outcome will be for your baby.
You will be referred to a doctor who is experienced in treating these disorders.
For more information on newborn screening, please contact your family doctor, registered midwife, or local public health unit.
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