Borderline positive (slightly abnormal) newborn screen for congenital hypothyroidism (CH) - HP7493
The full resource:
You have just learned that your baby has had a borderline (slightly abnormal) newborn screen. This information will answer some of your questions.
About newborn screening
A short time after your baby was born, some blood was collected from their heel to test for some rare disorders, including congenital hypothyroidism (CH). We screen newborns in this way to find conditions where early treatment can help babies to stay well.
Why your baby needs a second test
Your baby’s screening test for CH was borderline (slightly abnormal). The laboratory needs to retest your baby using a fresh sample to check the result.
Most babies with abnormal screening results do not have anything wrong.
Common reasons for a borderline CH result are:
- the testing card had too much blood on it
- the baby was exposed to iodine around the time that they were born
- the mother had thyroid antibodies.
About CH
A baby with CH is born with a thyroid gland that does not work properly.
Thyroid glands make thyroxine, a hormone which is important for normal growth and
development.
CH can be mild or severe. If a baby with a borderline result has CH, they are likely to
have a mild form of it.
Babies with CH remain healthy in the first weeks of life and usually have no signs or
symptoms. Please discuss any concerns with your midwife.
What happens next
Your midwife will arrange to collect a further blood spot (heel prick) sample from your baby and send the testing card to the laboratory. The laboratory will have the test result one to two days after it gets the sample. It will then call or text your midwife with the result.
In most cases the repeat sample is normal and babies do not need any more testing.
If the level is still not completely normal, your baby will be referred to a paediatrician for a full assessment. That assessment will include a blood test to check thyroid function.
If your baby does have a mild form of CH, the treatment is to give them a medicine to
replace the thyroxine hormone (which baby can’t make). When babies are treated for CH,
they become healthy children and adults.
Where to go for more information
For more information about newborn screening, go to Heel prick test — newborn metabolic screening
For more about what it is like to live with CH, see Lily and Milton’s stories at
https://www.nsu.govt.nz/pregnancy-newborn-screening/newborn-metabolic-screening-
programme-heel-prick-test/about-newborn/tell