Fact Sheet

Congenital Hypothyroidism

  • Editors
  • Rosalind S. Brown, MD
    Stephen LaFranchi, MD
    Susan R. Rose, MD

What is congenital hypothyroidism?

Newborn babies who are unable to make enough thyroid hormone have congenital hypothyroidism, meaning they are born with an underactive or absent thyroid gland.  If the condition is not found and treated, children can have mental retardation and growth failure.  But the good news is that early diagnosis and proper treatment can prevent these problems.  In most cases, the condition is permanent and your child will need lifelong treatment. 

Thyroid gland

What causes congenital hypothyroidism?


The most common causes are

 These abnormalities are not inherited from the parents.

Did you know?

About 1 in every 2,000 to 4,000 babies is born with congenital hypothyroidism.  It is twice as common in girls as in boys.

Other possible causes include

Less commonly, a mother’s thyroid disease or medicines taken during pregnancy can cause congenital hypothyroidism.

What does thyroid hormone do?

Thyroid hormone helps your baby’s brain and nervous system develop normally.  It also helps the heart, muscles, and other organs work properly.  Thyroid hormone regulates how the body uses and stores energy and how the body grows.  The thyroid gland makes two forms of thyroid hormone, T4 (thyroxine) and T3 (triiodothyronine).

What are the signs and symptoms of congenital hypothyroidism?

Many babies with congenital hypothyroidism appear normal at birth or for several months after birth.  But others may have these signs and symptoms:

They might also have

Thyroid hormone deficiency can also occur in older babies or young children, even if test results at birth were normal.  If your child shows signs and symptoms of hypothyroidism, contact your doctor right away.

How is congenital hypothyroidism diagnosed?

Most newborns in the United States are tested a few days after birth for congenital hypothyroidism as part of standard screening tests.  These tests detect almost all cases of congenital hypothyroidism.  Doctors check blood levels of

Low levels of T4 and high levels of TSH suggest a diagnosis of congenital hypothyroidism.  Doctors also might do a thyroid scan or an ultrasound exam to look at the size and location of the thyroid or to find out if it is missing altogether.

How is congenital hypothyroidism treated?

Every day, you will give a synthetic (laboratory-made) form of thyroid hormone to your baby to replace the missing thyroid hormone.  You’ll crush the hormone pill and mix it with a small amount of water, breast milk, or formula.  (Do not mix it with soy protein-based formulas, since they interfere with absorption of thyroid hormone.)  Then you’ll give it to your baby by mouth, using a medicine dropper, syringe, or open nipple.  Treatment begins as soon after birth as possible.  In most cases, your child will need to take daily thyroid hormone throughout life. 

Talk with your doctor about how often to have follow-ups.  The doctor will recommend blood tests to check your child’s hormone levels regularly, including one month after any dose change, to make sure your child is getting the right amount of hormone.  The doctor also will check your child’s growth and brain development. 

Questions to ask your doctor