Newborns with Congenital Hypothyroidism
Congenital hypothyroidism is very treatable, though newborns with untreated hypothyroidism are at risk for intellectual disabilities. When newborns are diagnosed and treatment starts within a few weeks of birth, growth and development are usually very normal. Some children will still have problems in school and with speech. Taking the medicine every day protects intelligence, normal growth, coordination and the heart.
Causes in Newborns
A few babies are born without a thyroid gland or with only a partially formed one. A few have part of or their entire thyroid in the wrong place. In some babies, the thyroid cells or their enzymes don’t work right. What causes congenital hypothyroidism in newborns is usually different than hypothyroidism that starts later.
- Structure of the thyroid gland: One cause of congenital thyroiditis is an abnormally formed thyroid gland. Almost always, the reason for this cannot be determined. The gland may be of normal size.
- Function of the thyroid gland: Sometimes, congenital hypothyroidism occurs because the thyroid gland isn’t able to make thyroid hormone. An error occurs in one of the steps. The gland enlarges into what is called a goiter.
- Problem in the pituitary gland: Rarely, the problem is that the pituitary gland isn’t making thyroid-stimulating hormone. This “master gland” should tell the thyroid how much hormone to make. A damaged pituitary may no longer be able to instruct the thyroid, and the thyroid may stop making enough hormone.
Diagnosis in Newborns
All states require that newborns have a blood test for congenital hypothyroidism. The test usually measures the amount of thyroid-stimulating hormone in the blood. Starting hormone replacement within weeks of birth makes it possible for a newborn with hypothyroidism to develop normally, free of brain damage and intellectual disabilities. Babies with hypothyroidism can look perfectly normal, so the screening test is critical. On average, Illinois’ Newborn Screening Program identifies 60 to 70 children with congenital hypothyroidism each year.
The initial test — requiring a prick of the heel to get droplets of blood — is done before the child is four or five days old (seven days at the latest if the child is premature, born at home or critically ill). Using a screening test is far better than relying on symptoms and signs because those are often mild and not noticed until the brain is damaged. Brain damage cannot be reversed.
Some symptoms in newborns:
- Prolonged jaundice (yellowish skin)
- Hoarse cry
- Poor appetite, poor feeding
- Bulging naval
- Doesn’t kick vigorously
- Unusually large tongue
As soon as something seems wrong (in the screening test or the baby), the pediatrician needs to refer the family to a pediatric endocrinologist. A second drop of blood must be tested. After two positive tests, hypothyroidism is diagnosed. Even after normal screening tests, an infant’s health care provider may have reason to test for hypothyroidism. The disorder can develop after birth.
Treatment for Newborns
The endocrinologist sets the starting dose of hormone replacement. Sometimes, signs and symptoms aren’t seen for a few weeks, but treatment must start within weeks of the birth to prevent intellectual disabilities and brain damage. Left untreated, the condition also leads to poor coordination, shakiness and unsteadiness. Adequately replacing the hormone is important to prevent learning delays and slow growth.
- Thyroid hormone replacement: Treatment is usually just one tablet of levothyroxine a day, taken around the same time each day. The tablet can be crushed and mixed with liquid, but not soy formula or formula containing iron. As the infant grows, the dose is increased. Older children simply chew or swallow the tablet.
- Blood test: A baby with congenital hypothyroidism needs to have a thyroid test every two to three months during the first year.