General Condition Information
- Congenital primary hypothyroidism
- Primary congenital hypothyroidism
- Primary hypothyroidism
- Over a thousand babies are born each year in the United States with this condition.
- Nearly twice as common in females compared to males.
What is Congenital hypothyroidism
Congenital hypothyroidism is a disorder that happens when the thyroid gland does not develop or work correctly.
In congenital hypothyroidism, the thyroid gland may be completely absent, or it may be too small or in the wrong place. In some cases, the thyroid may be normal-sized or even large. In all types of congenital hypothyroidism, the thyroid does not make enough of certain hormones that the body needs.
Babies with congenital hypothyroidism need treatment with medicines that replace the hormones normally made by the thyroid. If not treated, the low level of hormones leads to the signs and symptoms.
Newborn Screening and Follow-Up
Newborn screening for congenital hypothyroidism is done using a small amount of blood collected from your baby’s heel. To learn more about this process, visit the Blood Spot Screening page.
During screening, a special machine measures how much of certain substances (called thyroid stimulating hormone [TSH] and/or thyroxine [T4]) are in your baby's blood. Babies with low or normal levels of thyroxine and high levels of thyroid stimulating hormone might have congenital hypothyroidism.
If your baby’s blood spot screening result for congenital hypothyroidism is out-of-range, your baby’s health care provider will contact you. Together, you will discuss next steps and follow-up plans.
An out-of-range screening result does not mean that your baby definitely has congenital hypothyroidism. It does mean that your baby needs more follow-up testing. To learn more about screening results, visit the Blood Spot Screening Results page.
Your baby may need the following tests after an out-of-range screening result:
- Blood tests
- Picture of the thyroid (also called imaging, ultrasound, or uptake scan)
You should complete any recommended follow-up testing as soon as possible. Babies with this condition can have serious health problems early on if they are not diagnosed and treated quickly.
False-positive newborn screening results for this condition can happen. Some situations can affect screening results for congenital hypothyroidism:
- Screening samples were collected too early (before the baby is 24 hours old)
- Babies who were born early (premature) or had a low birth weight
- Babies who have very low levels of iodine
- Babies who are born to mothers with hyperthyroidism
False-negative newborn screening results also can happen. Babies who are born early may not make enough TSH to get an out-of-range result, even if they have congenital hypothyroidism. Babies who are treated with dopamine may also have false-negative results.
Newborn screening helps babies lead healthier lives. If your baby has an out-of-range result, follow up with your health care provider quickly. It is important to follow their instructions. Your baby may need to get treatment right away, even if they are not showing signs or symptoms. In some cases, your baby’s health care provider may decide it is best to watch (monitor) your baby to decide next steps. Careful monitoring and early treatment will help your baby stay as healthy as possible.
Babies with congenital hypothyroidism usually do not have symptoms at birth. It is important to treat the condition before symptoms appear. Signs of the condition may start three to four weeks after birth and include the following:
- Slow growth
- Floppy arms and legs (hypotonia)
- Increased sleep
- Difficulty feeding
- Yellow eyes or skin (jaundice)
- Large tongue (macroglossia)
- Cool, pale skin
- Large belly with a navel that sticks out
- Hoarse-sounding cry
Congenital hypothyroidism can be caused by a range of different factors.
Most cases of congenital hypothyroidism (80 to 85 percent) are caused when the thyroid gland does not develop properly. The reason this happens is often unknown and hard to predict. In these cases, congenital hypothyroidism is not passed down from the birth parents through genes (inherited). Siblings are not more likely to have the condition when genes are not involved.
About 15 to 20 percent of cases of congenital hypothyroidism are caused by changes in genes. When certain genes don’t work, the thyroid can develop incorrectly and not make enough hormones. In these cases, family members may be more likely to have the condition.
Congenital hypothyroidism may also be part of a syndrome. For example, many babies with Down syndrome (trisomy 21) also have congenital hypothyroidism.
In the uncommon cases where congenital hypothyroidism is caused by changes in certain genes, babies inherit it from their biological (birth) parents. To learn more about genetic conditions, visit MedlinePlus Genetics.
- In genetic causes of congenital hypothyroidism, it is usually inherited in an autosomal recessive pattern. This means that babies inherit the condition when each parent passes down a nonworking gene to their baby. Only babies with two nonworking genes—one from the mom and one from the dad—have this condition.
- People with one working copy and one nonworking copy of the gene are called carriers.
- Carriers do not have or develop the condition. However, they may pass down a nonworking copy of the gene to their children.
- If two parents are carriers of a nonworking copy of the gene, they have a 1 in 4 chance of having a child with congenital hypothyroidism.
- Carriers for congenital hypothyroidism often do not know they are carriers before having a child with the condition. In most cases, families have no history of the condition until the birth of a child with congenital hypothyroidism.
- Parents who already have a child with congenital hypothyroidism due to a change in their genes still have a 1 in 4 chance of having another child with congenital hypothyroidism. This 1 in 4 chance stays the same for all future children.
- Genetic counselors and medical geneticists can help families learn about this condition and the chance of having children with it. Visit the National Society of Genetic Counselors to find a genetic counselor and the American College of Medical Genetics and Genomics to find a medical geneticist.
Treatment and Management
It is important to talk to your health care provider about which treatment(s) are best for your baby. The goal of treatment is to prevent the health problems caused by this condition.
Treatments may include the following:
- Treatment with thyroid hormones
- Limited soy and iron, as these can affect absorption of the thyroid hormone medications
Children who receive early and ongoing treatment for congenital hypothyroidism can have healthy growth and development; however, thyroid hormone levels will need to be checked throughout your child’s life.