How Do Doctors Test for Congenital Hypothyroidism?

Most often, congenital hypothyroidism is discovered through the newborn screening test. All babies have this test when they are born. A newborn screening test screens your baby for congenital hypothyroidism as well as other diseases that can affect newborns.

For the newborn screening test, we take a few drops of blood from your baby’s heel soon after he or she is born. The test results are sent to your baby’s pediatrician.

When a baby’s newborn screening test shows possible congenital hypothyroidism, we repeat the thyroid labs using a blood test. For this, we take a small amount of blood from a vein in your baby’s arm. The blood test will check the level of thyroid hormone in your baby’s blood. Blood tests also help us figure out how much medication to give your baby, and whether the amount of medication we are giving is the right amount.

Sometimes, we might also have your baby get a thyroid scan. This helps us determine how well your baby’s thyroid gland has developed and if it is in its usual position in the front of the neck. When the thyroid gland is not in the right position, we call this an ectopic thyroid gland. This is important in determining whether your baby might receive a trial off medication at 3 years.

How Do Doctors Treat Congenital Hypothyroidism?

We treat your baby’s congenital hypothyroidism with a medication called levothyroxine. This is the natural thyroid hormone that your baby’s thyroid cannot make and is taken in the form of a pill. There are different brand names for levothyroxine.

The dose of levothyroxine is adjusted as your baby grows to keep your baby’s thyroid hormones at a normal level.

How Do Doctors Monitor Treatment for Congenital Hypothyroidism?

Your baby will need blood tests so we can check his or her thyroid hormone levels and adjust his or her levothyroxine dose accordingly.

Your baby’s endocrinologist or pediatrician will ask you to bring your baby in for blood tests every 1-2 months during the first year of life, every 2-3 months in the second and third years, and every 4-6 months after your baby’s third year.

During your baby’s first 3 years, it is very important that his or her thyroid hormone levels are in the normal range. This will help make sure that your baby’s brain develops properly.

Most children will need treatment throughout their life. For some children, hypothyroidism is mild and temporary. Sometimes, your child might be given a brief trial off medications after 3 years of age. Your child would then be retested to see if medication needs to be restarted.

It is very important that you keep your doctor’s appointments and give your baby the medicine every day.

What is the Long-Term Outlook for Congenital Hypothyroidism?

Your baby should do well and be healthy if we treat him or her early and with the right dose of medication.

If your baby’s treatment is delayed or the dose of thyroid hormone given is too low, it may affect his or her development, learning and school performance.

Rev. 4/2015. MassGeneral Hospital for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so that you can be better informed. It is not a substitute for medical advice and should not be used to treatment of any medical conditions.