Disorder Name: Congenital Hypothyroidism
This fact sheet contains general information about congenital hypothyroidism (CH). Every child is different and some of these facts may not apply to your child specifically. Certain treatments may be advised for some children but not others.
What is CH?
The thyroid gland is a butterfly-shaped organ at the base of the neck. Its job is to make specific hormones that help the cells of the body function correctly. The main hormone made by the thyroid gland is thyroid hormone, also called ‘thyroxine’, or T4. It is released by the thyroid gland into the bloodstream whenever it is needed by the body. It helps cells work more efficiently and also helps raise our body temperature. In babies and young children, thyroid hormone is crucial for normal growth and development of the body and brain.
People with hypothyroidism have specific symptoms and health issues. Babies who do not have enough thyroid hormone are often slow to grow, are sluggish, and have learning delays and other specific health problems. There are number of different causes for CH which are mentioned below.
What causes CH?
CH can be the result of a number of different underlying causes.
Missing or misplaced thyroid gland
In healthy people, the thyroid gland is located in the center of the front of the neck, near the top of the windpipe. In some children with CH, the thyroid gland may instead be under the tongue or on the side of the neck. If the thyroid gland is in the wrong place, or if it is underdeveloped, it often does not work well and makes less thyroid hormone than needed by the body. If the thyroid gland is missing, the baby cannot make any of its own thyroid hormone. A missing, underdeveloped or misplaced thyroid gland is a birth defect that happens for unknown reasons and is usually not inherited.
Maternal iodine deficiency
Maternal thyroid condition and medications
If CH is not treated, what problems occur?
Most babies do not have symptoms right away because they are protected by their mother’s thyroid hormone for a few weeks after birth. After about three to four weeks of age babies must rely solely on their own thyroid hormone. If they don’t make enough, symptoms will show up at that time. A small number of babies with CH do show effects at birth, however.
Some babies have a yellow color to their skin or the whites of their eyes. This is called jaundice. Other signs that may occur in early infancy include:
If left untreated, babies may develop some or all of the following effects over time:
Children who remain untreated usually become mentally retarded and are much shorter than average. They may have spasticity and an unsteady gait. Most have speech delays and some have behavior problems.
What is the treatment for CH?
Your baby’s doctor may work with a pediatric endocrinologist, a doctor with training in treating children with thyroid and other hormone problems, to care for your child.
The main treatment for CH is thyroid hormone replacement. It is safe and easy to take. If it is begun immediately after your child is diagnosed, treatment can prevent many or all of the effects of CH. If damage to the brain and nerves happens because treatment is delayed, it is usually permanent and cannot be reversed.
L-thyroxine tablets are small and can be crushed into food or dissolved into a small amount of formula, juice or other liquid. Do not dissolve them into a full bottle or glass of liquid because your baby may not finish the whole bottle and will not get the full dose of medicine. Young children can easily chew and swallow the pills. There is no approved liquid form of thyroid hormone.
It is important to give your child the correct amount of L-thyroxine. Giving your child more than he or she needs can cause body functions to speed up. Some of the signs that occur when a child takes too much L-thyroxine are:
Synthetic L-thyroxine is the safest form of medication to use. In the past, before synthetic forms were available, children were treated with dried thyroid hormone from pooled animal tissue. This is called ‘dessicated thyroid’ and is still available. Do not use dessicated thyroid as the dose of hormone is not consistent.
Soy-based formulas and iron supplements can reduce the amount of thyroid hormone your baby absorbs from the pills. Tell your doctor if you feed your baby a soy-based formula or iron supplements so the medication can be monitored and increased if necessary.
3. Developmental Evaluation
What happens when CH is treated?
Children with CH who start treatment soon after birth usually have normal growth and intelligence and can live typical and healthy lives. Some children, even when treated, have problems with school work and may need extra help. Some may have delayed growth compared to other children their age.
If treatment is not started until several months after birth, delays or learning problems may occur. The level of delay varies from child to child.
How do I know if my child’s CH is inherited?
About 80 to 85% of the time, CH is caused when the thyroid gland does not develop at all, is misplaced, or is too small. Most of the time, these cases are not thought to be caused by inherited factors.
In about 15% of cases of CH, the thyroid gland appears normal but the amount of thyroid hormone made is reduced. These cases are more likely to be inherited, but not always. If an inherited form of CH is suspected, you may be referred to a genetic doctor or genetic counselor to determine whether the CH is inherited.
Most of the hereditary types of CH are inherited in an autosomal recessive manner. This type of inheritance affects both boys and girls equally. In children with autosomal recessive CH, a specific pair of genes is not working correctly and too little thyroid hormone is made. These children inherit one non-working gene for the condition from each parent. These children have a normal appearing thyroid that is in the correct place in the neck but does not make enough thyroid hormone.
Parents of children with autosomal recessive CH rarely have the condition themselves. Instead, each parent has a single non-working gene for CH. They are called carriers. Carriers do not have CH because the other gene of this pair is working correctly.
When both parents are carriers, there is a 25% chance in each pregnancy for the child to have CH. There is a 50% chance for the child to be a carrier, just like the parents. And, there is a 25% chance for the child to have two working genes.
In very rare cases, CH may be inherited in a different way, either by an X-linked recessive or autosomal dominant gene. If your child has one of these rare inherited types of CH, your genetic counselor or genetic doctor will explain how it is inherited and who else in the family may have a chance to pass on the gene for CH.
Genetic counseling is available to families who have children with CH that might be inherited. Genetic counselors can answer your questions about how the CH could be inherited in your family, chances for CH in future offspring. If you have questions, ask your doctor for a referral to a genetic counselor.
If my child might have an inherited form of CH, is genetic testing available?
There are a number of different genes that can contribute to hereditary CH. Some of these are known and some have still not been identified.
If a genetic doctor suspects an inherited form of CH, genetic testing may be available to attempt to determine the gene changes that caused the CH. Genetic testing, also called DNA testing, can be done on a blood sample.
DNA testing is not necessary to diagnose your child. If the gene change or changes are identified in your child, this may be helpful for carrier or prenatal testing, discussed below.
What other testing is available?
If your baby has a positive newborn screen for CH, additional tests must be done before you know for sure that he or she has CH. Blood tests to detect the amount of thyroid hormone (T4) and thyroid stimulating hormone (TSH) are routinely done to confirm the diagnosis of CH. Talk to your doctor if you have questions about testing for CH.
Sometimes an imaging test of the thyroid, either an ultrasound examination or another test called a ‘thyroid uptake and scan’, is used to help determine the cause for the CH. This lets doctors see if the thyroid is present, where it is located and if it is misshapen or smaller than normal.
Can you test during pregnancy?
CH is not usually detectable before birth and most children with CH do not have a hereditary form. For those that may have an inherited form, genetic testing can confirm only a portion of the hereditary cases.
If your child has a hereditary form of CH, and if the gene change(s) have been found in your child, DNA testing is possible during future pregnancies. However, prenatal testing is rarely done for CH because treatment is so effective. If you have questions about prenatal testing, ask your genetic counselor or physician.
Can other members of the family have CH?
How many people have CH?
Does CH happen more frequently in a certain ethnic group?
CH occurs in people of all ethnic groups around the world. It happens more often in babies from parts of the world in which there is not enough iodine in the food and water. It is also more common in babies of Hispanic and Native American ancestry. It is less common in babies of African-American ancestry.
Does CH go by any other names?
CH is sometimes also called:
Where can I find more information?
MAGIC Foundation (Major Aspects of Growth in Children)
National Library of Medicine Genetics Home Reference (Congenital Hypothyroidism)
The Thyroid Foundation of America
|Legal Disclaimer/Funded by HRSA/MCHB