Babies born with CHT do not make enough of a hormone called thyroxine. Thyroxine is a chemical made by a gland in the neck called the thyroid.
Babies with CHT may not have a fully formed thyroid, or it may be missing.
Sometimes the thyroid is normal, but it may not be producing thyroxine.
Babies who do not produce enough thyroxine can have growth problems or disabilities.
Babies born in Ireland with CHT
Around 1 in every 1,000 babies born in Ireland has CHT.
In most cases CHT does not have a known cause. Only a very small number of cases are inherited (passed down by family).
How heel prick screening can help
Babies are screened for CHT as part of heel prick screening. They are offered heel prick screening when they are around 5 days old. This test also checks for other conditions.
A midwife or nurse takes a few drops of blood from your baby's heel using a special device.
If the heel prick suggests your baby may have CHT, they will be referred to a specialist.
If CHT is confirmed, your baby can get medicine to replace the missing thyroxine.
If treatment starts early, your baby will develop normally. The treatment is usually for life. The dose is adjusted as your baby grows.