Conditions Primary Congenital Hypothyroidism

Primary congenital hypothyroidism (CH) is a condition that affects the body’s thyroid gland, a small organ in the lower neck. People with CH are unable to produce enough thyroid hormone, a chemical that is essential for healthy growth and development. If left untreated, CH can cause sluggishness, slow growth, and learning delays. However, if detected early and treatment is begun, individuals with CH often can lead healthy lives.

Condition Type

Endocrine Disorders


In the United States, about one in every 3,000 to 4,000 babies is born with congenital hypothyroidism (CH). Twice as many females as males are affected by CH.

Also known as

  • CH
  • CHT
  • Congenital myxedema
  • Congenital hypothyroidism

Follow-Up Testing

Your baby’s doctor may ask you if your baby is showing any of the signs of CH (see Early Signs, below). If your baby has certain signs, your baby’s doctor may suggest starting immediate treatment.

If your baby’s newborn screening result for primary congenital hypothyroidism (CH) was out of the normal range, your baby’s doctor or the state screening program will contact you to arrange for your baby to have additional testing. It is important to remember that an out-of-range screening result does not necessarily mean that your child has the condition. An out-of-range result may occur because the initial blood sample was too small or the test was performed too early. However, as a few babies do have the condition, it is very important that you go to your follow-up appointment for a confirmatory test. Because the harmful effects of untreated CH can occur soon after birth, follow-up testing must be completed as soon as possible to determine whether or not your baby has the condition.

Follow-up testing will involve testing baby’s blood. Individuals with CH are unable to make enough of a thyroid hormone, so a low level of thyroid hormone in the blood may indicate that your baby has CH. When the thyroid is not functioning properly, the body produces more of a chemical called thyroid stimulating hormone in an attempt to get the body to produce more thyroid hormone. A high amount of thyroid stimulating hormone can be a sign of CH.

Most cases of CH (around 85 percent) are caused when the thyroid gland is missing, misplaced, or too small. Your baby’s doctor may recommend an imaging test of the thyroid, which can be an ultrasound or another test called a thyroid uptake and scan. In the thyroid uptake and scan test, a very small and safe amount of radioactive material will go into your baby’s body, either by mouth or through an injection. After 6-24 hours, the radioactive material will have collected in the thyroid, and an imaging machine can create a picture of the thyroid. Your baby may need to follow a special diet or fast for a short period before the test.

About Primary Congenital Hypothyroidism

Early Signs

Most babies with primary congenital hypothyroidism (CH) show signs at three to four weeks after birth. Early signs of CH include:

  • Yellow skin or eyes (known as jaundice)
  • Sleeping longer or more often
  • Constipation
  • Weak muscle tone (called hypotonia)
  • Swelling around the eyes
  • Swollen tongue
  • Cool, pale skin
  • Large belly with a navel that sticks out
  • A hoarse-sounding cry
  • Delayed growth and weight gain

Contact your baby’s doctor as soon as possible if your baby has any of these signs.



The most common treatment for primary congenital hypothyroidism (CH) is thyroid hormone replacement therapy. Your baby may need to take L-thyroxine pills, a synthetic thyroid hormone, to replace the natural thyroid hormone that their body does not make enough of. An endocrinologist can help determine the appropriate amount of L-thyroxine for your baby and write a prescription (see Accessing Care).

Dietary Restrictions

If your baby is taking thyroid hormone pills, you may need to restrict the amount of soy and iron in their diet. Soy and iron affect how the body absorbs thyroid hormones from the pills. Tell your baby’s doctor if your baby eats soy-based formula or takes iron supplements.

Expected Outcomes

If treatment starts soon after birth, children with primary congenital hypothyroidism (CH) can have healthy growth and development. This is why newborn screening for CH is so important.

Treatment will need to continue throughout your child’s life. This may require regular check-ups to monitor thyroid hormone levels, growth, and development.

Some children may still have trouble in school or delayed growth, even with treatment. Children who struggle in school may need extra help or an early intervention program to prepare them for school.

Delayed treatment can put children at risk for intellectual disabilities, learning disabilities, developmental delays, and delayed growth.


In our bodies, glands make hormones. Hormones send messages to cells throughout the body. These messages control all sorts of functions, such as breaking down food or mental and physical development.

Primary congenital hypothyroidism (CH) occurs when the thyroid gland is not working properly. The thyroid gland is a gland in the neck that makes a hormone called thyroid hormone. Thyroid hormone helps control growth, brain development, and how we break down food for energy.

About 80 to 85 percent of CH cases are sporadic. This means that:

  • The condition was not passed on from parent to child.
  • An affected individual cannot pass this condition on to their children.
  • Brothers and sisters are usually not at risk of having CH.

In these cases, the thyroid gland does not develop correctly. It may be completely missing, located in the wrong place, or too small to make enough thyroid hormone.

About 15 percent of CH cases are considered to have a genetic cause.

In this case, CH is usually an autosomal recessive genetic condition. This means that a child must inherit two copies of the non-working gene for CH, one from each parent, in order to have the condition. The parents of a child with an autosomal recessive condition each carry one copy of the non-working gene, but they typically do not show signs and symptoms of the condition. While having a child with CH is rare, when both parents are carriers, they can have more than one child with the condition. Learn more about autosomal recessive inheritance.

A geneticist or genetic counselor can help you determine if your child has an autosomal recessive genetic case of CH. All the ways genetic-based CH is inherited are not yet well understood. CH may also be inherited by autosomal dominant or X-linked recessive patterns.

In very rare cases, CH is caused by an iodine deficiency in the mother during pregnancy. Iodine is a natural substance that the thyroid gland needs for healthy development. If a pregnant woman does not consume enough iodine, her baby may be at risk for CH. Anti-thyroid drugs can also put a developing baby at risk for CH.

Support for Primary Congenital Hypothyroidism

Support Services

Support groups can help connect families who have a child or other family member affected with primary congenital hypothyroidism with a supportive community of people who have experience and expertise in living with the condition. These organizations offer resources for families, affected individuals, health care providers, and advocates.

Accessing Care

Work with your baby’s doctor to determine the next steps for your baby’s care. Your baby’s doctor may help you coordinate care with an endocrinologist, a physician who treats children with thyroid and other hormone or endocrine concerns. Depending on the signs and symptoms of your baby’s condition, your baby’s doctor may help you coordinate care with other medical resources in the community. Some children with primary congenital hypothyroidism (CH) have developmental delays. If you think that your baby is not meeting their developmental milestones, ask your baby's health care provider about the next steps in accessing a developmental evaluation and care.

Because CH is a genetic condition, you may want to talk with a genetics specialist. A genetic counselor or geneticist can help you understand the causes of the condition, discuss genetic testing for CH, and understand what this diagnosis means for other family members and future pregnancies. Speak with your baby’s doctor about getting a referral. The Clinic Services Search Engine offered by the American College of Medical Genetics and Genomics (ACMG) and the Find a Genetic Counselor tool on the National Society of Genetic Counselors (NSGC) website are two good resources for you or your baby's health care provider to use to identify local specialists.

Families' Experiences

Margot was diagnosed with congenital hypothyroidism through newborn screening at birth. Her mother writes about how scared she was when Margot was diagnosed, but with treatment Margot is staying healthy. Read Margot’s story on her mother’s blog.

Lucia was diagnosed with congenital hypothyroidism through newborn screening. Her mother, a doula and childbirth educator, writes about how grateful she is for newborn screening and how she will use her experience to educate other families about the program. Read Lucia’s story on the Minnesota Newborn Screening Program website.

References & Sources

Visit the Screening, Technology And Research in Genetics (STAR-G) Project for more information on CH

Read this guide from the New York Times about radioactive iodine uptake

Visit MedlinePlus Genetics for more condition information

ACT Sheets

Healthcare professionals can learn more about confirmatory testing by reading the American College of Medical Genetics and Genomics' Algorithm for Diagnosis and ACT Sheet, a guide for follow-up after newborn screening. You can visit this page of the ACMG website here.

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