OTHER DISORDER

Disorder Name:  CongenitalThis means ‘present at or before birth.’ It usually refers to health conditions or birth defects that are present in a baby at or prior to birth. HypothyroidismThis is a condition in which the person does not make enough thyroid hormone. It is most common in adult women and causes symptoms such as cold, pale, dry skin, brittle hair and nails, fatigue, weight gain and sluggishness. When the thyroid is not making enough hormone at birth, it is called congenital hypothyroidism. Hypothyroidism is treated by a medication that replaces the natural thyroid hormone the person cannot make on his or her own.
Acronym:  CH
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• What is CH?
• What causes CH?
• If CH is not treated, what problems occur?
• What is the treatment for CH?
• What happens when CH is treated?
• How do I know if my child’s CH is inherited?
• If my child might have an inherited type of CH, is genetic testing available?
• What other testing is available?
• Can you test during a future pregnancy?
• Can other members of the family have CH?
• How many people have CH?
• Does CH happen more often in a certain ethnic group?
• Does CH go by any other names?
• Where can I find more information?

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?

CH stands for “congenital hypothyroidism.”  Congenital means present at birth. Hypothyroidism is a condition in which the person does not make enough thyroid hormone.

The thyroid gland is a butterfly-shaped organ at the base of the neck.  Its job is to make specific hormonesHormones include many different types of chemicals that act as messengers around the body. Hormones are made by specific endocrine glands and are secreted into the blood when needed by other parts of the body. Hormones travel to other organs and tissues in the body to signal them to do something. For example, insulin is a hormone that signals muscle and fat cells to remove glucose from the blood and enter the cells. that help the cellsThe smallest living unit. Cells make up all organs and tissues in multi-cellular organisms, like humans. They can also live independently, as in bacteria and other microorganisms. At a minimum, a cell is surrounded by a membrane, contains DNA at some stage in its life, and is able to replicate itself into two equal parts. of the body function correctly. The main hormone made by the thyroid gland is thyroid hormone, also called ‘thyroxineThyroxine, also called T4, is the major thyroid hormone made by the thyroid gland. One of the essential components of thyroxine is iodine. This is why iodine deficiency results in hypothyroidism and goiter.,’ 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 maintain 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 a 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
Most babies with CH are missing their thyroid gland or have a thyroid that did not develop properly.  In some cases, the thyroid gland may be smaller than usual or may not be located in the correct place.

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 inheritedAcquiring a trait from one’s parents. Most traits, such as eye color or hair color, are inherited from a parent through genes..

HereditarySomething that is passed on from a parent to the child, usually through the genes. causes
Less often, CH is caused by inherited changes in a gene or pair of genesA segment of DNA that contains the instructions to make a specific protein (or part of a protein). Genes are contained on chromosomes. Chromosomes, and the genes on those chromosomes, are passed on from parent to child. Errors in the DNA that make up a gene are called variants and can lead to diseases..  This is explained in more detail below.  Children with the inherited type of CH do not make enough thyroid hormone even though their thyroid gland appears normal in size and shape.  About 15% of children with CH are thought to have an inherited type.

MaternalHaving to do with the mother. iodineThis is an element needed in order for the body to make thyroid hormone. It is found in certain foods such as shellfish, seafood and seaweed. Without enough iodine in the diet, a person will develop hypothyroidism and possibly a goiter. In the United States, iodine deficiency is rare because iodine is added to table salt (iodized salt). deficiency
If the mother is deficient in iodine during the pregnancy, the fetal thyroid gland may not be able to make enough thyroid hormone.  The baby is then born with CH.  This is a problem in some parts of the world where people do not get enough iodine in their diet.  This is a very rare cause for CH in the United States because our table salt is supplemented with iodine (‘iodized salt’). Other foods, in particular dairy products, contain iodine, as well.

Maternal thyroid condition and medications
In a small number of cases, CH occurs when the mother is given anti-thyroid drugs during pregnancy to treat her own thyroid problem.

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 jaundiceThis is a yellow color to the skin and whites of the eyes. It is often a sign of liver damage..  Other signs that may occur in early infancy include:

• Low activity level – babies sleep more than usual and don’t move as much
• Poor feeding and poor suck
• Fewer bowel movements or constipation
• Floppy muscle toneIn order to hold our posture and control our movements, a certain amount of tension is needed in our muscles. This tension is called “muscle tone.” People with hypotonia have too little tension in their muscles and appear “floppy.” People with hypertonia have too much tension in their muscles and have problems with tight, rigid muscles and joints. (hypotoniaThis is a decrease in muscle tone that leads to loose or weak muscles and joints. Babies with hypotonia may have limbs and joints that feel “floppy” like a rag-doll. It can be caused by brain damage, muscle disorders or genetic conditions.)
• Swelling around the eyes and a puffy face
• Large swollen tongue
• Cool, pale, dry skin
• Large soft spot on the skull (the fontanelThese are the areas on the top middle of a baby’s skull that are covered by membranes and skin but not yet by bone. They are also called the ‘soft spots.’ The anterior fontanel is located in the front of the skull just above the forehead. It is the largest soft spot and should be closed by about 18 months. Babies with untreated congenital hypothyroidism may have very large fontanels that are delayed in closing.) that closes late
• Large belly with protruding navel (‘umbilical hernia’)

If left untreated, babies may develop some or all of the following effects over time:

• Coarse, swollen facial features
• Breathing problems
• Hoarse-sounding cry
• Delays in sitting, crawling, walking, talking (delayed milestones)
• Wide, short hands
• Poor weight gain and growth
• Goiter (enlarged thyroid gland causing a lump in the neck)
• AnemiaThis is a condition in which the blood has too few red blood cells or too little hemoglobin, the oxygen carrying molecule in the blood. People with anemia are often pale, tired, weak, dizzy and short of breath.
• Slow heart rate
• Fluid build-up under the skin (called myxedemaThis is a condition seen in people with hypothyroidism. It causes swelling of the skin and an enlarged tongue. People with myxedema develop thick and puffy eyes, cheeks, lips and nose. Dry skin also occurs. Myxedema symptoms go away once the hypothyroidism is treated.)
• Hearing loss

Children who remain untreated usually develop intellectual disabilities and are much shorter than average. They may have spasticity and an unsteady gait.  Most have speech delay and some have behavior problems.

WHAT IS THE TREATMENT FOR CH?  

Your baby’s doctor may work with a pediatric endocrinologistThis is a doctor with special training in endocrine conditions –disorders caused by problems with one or more endocrine glands and their hormones. Some of the endocrine glands in the body include the adrenal glands above the kidneys, the pituitary glands, the pancreatic islets, and the thyroid glands. Some endocrine conditions include diabetes, hypothyroidism and congenital adrenal hyperplasia., 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.

1. Medication
L-thyroxine is a synthetic form of thyroid hormone naturally made by the body. Its chemical structure is identical to that produced by the normal thyroid gland. This medication is given in tablet form to all babies with CH. Your doctor and endocrinologist will decide how much L-thyroxineThis is the most common synthetic form of thyroxine (thyroid hormone). It is given in pill form to children or adults who have hypothyroidism. It is important that the pills be taken on a daily basis. Stopping this medication causes the symptoms of hypothyroidism to return. your baby needs and how often. Your doctors will increase the amount of medication as your child grows. L-thyroxine needs to be taken on a daily basis throughout your child’s whole life.

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 for babies.

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:

• Rapid heart rate
• Diarrhea
• Lack of sleep
• Shakiness

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 ironIron is a natural element that is needed for the body to function properly. Iron can be found in many foods. Having a high amount of iron can cause damage to organs. Talk with your doctor about the risks and benefits if your child takes iron supplements or has blood transfusions. supplements can reduce the amount of thyroid hormone your baby absorbs from the pills. Separate the time you administer your baby’s thyroid medication by at least one hour from the time you feed soy formula or iron medication. 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.

2.  Monitoring
Your child will need regular visits to the doctor to check his or her weight, height, development, and overall health.  Your child will also likely need regular blood tests to check the level of thyroid hormone.  Blood tests are usually done every one to three months until age one, and then every two to four months until age three. They can usually be done less often after age three.

3.  Developmental Evaluation
Your doctor may suggest a formal evaluation of your child’s development.  If your child shows delays in certain areas of learning or speech, extra help can be arranged.  Early intervention programs are available in most states to provide services to children before they reach school age.

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 type of CH is suspected, you may be referred to a geneticRelating to (or due to) genes and heredity or the field of studying genes and heredity. doctor or genetic counselorThese are health care providers who have special training in genetic conditions. They help families understand genetic disorders and how they are passed down. Genetic counselors offer information and support to people who have genetic conditions in their families or are concerned that they may have a child with an inherited disorder. 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 recessiveMost of the metabolic disorders that can be detected by newborn screenings are inherited in an “autosomal recessive” pattern. Autosomal recessive conditions affect both boys and girls equally. How autosomal recessive inheritance works: Everyone has a pair of genes for each enzyme in the body. A separate pair of genes is responsible for making each enzyme. A person with a metabolic disorder has one enzyme that is either missing or not working properly. The problem is caused by a pair of “recessive” genes that are not working correctly. They do not make the needed enzyme. A person has to have two non-working “recessive” genes in order to have an autosomal recessive metabolic disorder. A person with an autosomal recessive disorder inherits one non-working gene from his or her mother and the other from his or her father. The parents are called carriers for that condition. Parents of children with a metabolic disorder rarely have the disorder themselves. Instead, for that pair of genes, each parent has one that is working correctly and one that is not working (called the “recessive” gene). People with a single non-working gene are called carriers. If one gene of the pair is working correctly, it makes up for the recessive non-working gene. Therefore, carriers usually will not have the condition. 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 carriersA person who has one copy of a gene mutation for a particular autosomal recessive disorder (remember genes come in pairs). Carriers are not affected by the disorder. However, they can pass on the gene variant to their children. Children who inherit two such gene variants will be affected by the disorder. The term variants is now used in place of the term mutation.. Carriers do not have CH because their other gene 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-linkedA mode of inheritance. X-linked genes are found on the X chromosome. They have a different inheritance pattern than other genes because women have two X chromosomes while men only have one. Any mutation on the X chromosome may not cause a disease in women if the gene on the other chromosome is normal. However, that same mutation on one X chromosome in men will cause the disease because they have no second copy of the gene to compensate. 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 and 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 TYPE 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 type 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.

DNADeoxyribonucleic acid (DNA) is a molecule found in the chromosomes that carries genetic information. DNA is composed of four units (called bases) that are designated A, T, G, and C. The sequence of the bases spell out instructions for making all of the proteins needed by an organism. A gene is a section of DNA that holds the instructions for a specific protein. A change in one or more of the DNA bases making up a gene is called a mutation. Some mutations change the protein instructions and can lead to particular health problems or disorders. Each parent passes half of their chromosomes, and thus half of their DNA instructions, onto their children. It is these instructions that cause certain traits, such as eye or hair color, to be inherited. 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 ultrasoundUltrasound is an imaging method that uses high-frequency sound waves to create an image of structures within a person’s body. Also see fetal ultrasound. examination or another test called a ‘thyroid uptake and scanThis is an imaging test that looks at the structure and function of the thyroid gland. It can show whether the thyroid is in the normal place, has a normal size and whether it is working correctly. The scan is done by injecting a small amount of radioactive material into a vein or having the patient swallow it by mouth. The material collects in the thyroid gland so an imaging machine can create a picture of the thyroid.,’ 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 A FUTURE PREGNANCY?

CH is not usually detectable before birth, and most children with CH do not have a hereditary type. For those that may have an inherited type, genetic testing can confirm only a portion of the hereditary cases.

If your child has a hereditary type of CH, and if the gene changes, also called variantsA variant is a change or alteration in a person’s DNA sequence. Variants can happen in genes and affect how the gene functions. There are different types of variants – they can be non-problem causing (benign), disease-causing (pathogenic) or of unknown significance. The term variants is now used in place of the term mutation., 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?

Having CH
If they are healthy and developing normally, older brothers and sisters of a baby with CH are unlikely to have the condition. Talk to your doctor if you have questions about your other children.

Future pregnancies
All 50 US states offer newborn screening for CH. However, when a previous child in the family has had CH, newborn screeningA screening test that looks for different disorders using a small sample of blood taken from a newborn’s heel. A positive or abnormal newborn screening result means that there are slight differences that were found in the baby’s blood, and further testing is needed to figure out if the baby has a metabolic disorder. results may not be sufficient to rule out the condition in a newborn baby. In this case, special diagnostic testing may be advised in addition to newborn screeningThe process of testing for disease in a person who does not show signs of having the disease (nonsymptomatic or asymptomatic person). The goal of screening is to catch the disease in its early stages..

HOW MANY PEOPLE HAVE CH?

About one in every 2,000 to 4,000 babies born in the United States has CH.  Twice as many girls have CH than boys. The reason for this is unknown.

DOES CH HAPPEN MORE OFTEN 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, Asian, South Pacific, 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:

• CHT
• Cretinism
• Endemic Cretinism (iodine deficiency)
• Congenital Myxedema

WHERE CAN I FIND MORE INFORMATION?

MedlinePlus
https://medlineplus.gov/genetics/condition/congenital-hypothyroidism/

The Endocrine Society
https://www.endocrine.org/

MAGIC Foundation (Major Aspects of Growth in Children)
www.magicfoundation.org

American Thyroid Association
https://www.thyroid.org/

DOCUMENT INFO:

Created by:	www.newbornscreening.info
Reviewed by:	HI and OR endocrine specialists
Review date:	December 12, 2012 June 3, 2020 March 8, 2023
Update on:	March 8, 2023

 

DISCLAIMER:

THIS INFORMATION DOES NOT PROVIDE MEDICAL ADVICE. All content (“Content”), including text, graphics, images and information are for general informational purposes only. You are encouraged to confer with your doctor or other health care professional with regard to information contained on this information sheet. After reading this information sheet, you are encouraged to review the information carefully with your doctor or other healthcare provider. The Content is not intended to be a substitute for professional medical advice, diagnosis or treatment. NEVER DISREGARD PROFESSIONAL MEDICAL ADVICE, OR DELAY IN SEEKING IT, BECAUSE OF SOMETHING YOU HAVE READ ON THIS INFORMATION SHEET. This project is supported by a grant from the Maternal and Child Health Bureau, Health Resources and Service Administration, Genetic Services Branch, MCH Project #UH7MC30774-01-00 http://mchb.hrsa.gov