Hypothyroidism in Infants and Children

What Is Hypothyroidism in Infants and Children

Hypothyroidism in infants and children occurs when too little thyroid hormone is produced by the thyroid gland, leading to low levels of thyroid in the bloodstream. The “underactive” thyroid gland does not make enough thyroid hormone, interfering with growth, physical and mental development, and other body processes.

  • Infants and small children affected by hypothyroidism may have significant problems with growth and development if the condition is not diagnosed and treated promptly.
  • In older children and young adults, hypothyroidism can cause diverse symptoms. Lack of thyroid hormone can lead to slowed heart rate, chronic tiredness, inability to tolerate cold, mental fatigue and difficulty in learning, constipation, weight gain, and other problems.

Hypothyroidism can develop at any point in the lifespan. Infants can be born with hypothyroidism, and hypothyroidism can develop in children and adults of any age.

For a more detailed explanation of the thyroid gland, thyroid hormones (T3 and T4) and how affect they the body, and regulation of thyroid hormone production, see What is Hypothyroidism?


Nice To Know:

Q: We adopted a baby from another country and brought him home when he was about four months old. Our pediatrician sent us to an endocrinologist, and he says our little boy has hypothyroidism. He also used the terms congenital hypothyroidism and cretinism. What do those terms mean?

A: Congenital hypothyroidism is hypothyroidism that is present at birth. You may see it abbreviated as CH.

Cretinism is a term for abnormal growth and mental retardation due to untreated congenital hypothyroidism. Neither term is associated with any specific cause of hypothyroidism. The doctor will determine what is the cause of the hypothyroidism. You will begin to feel better as you learn more about the particulars of your son’s condition and as he begins to respond to thyroid hormone treatment.

Facts about hypothyroidism in children

  • In North America, hypothyroidism present at birth is found in about 1 in every 4,000 newborns.
  • In about 10% of newborns with hypothyroidism, it is a temporary condition that will resolve within days or months.
  • About 95% of cases of childhood hypothyroidism are caused by a problem within the thyroid gland or by lack of a thyroid gland.
  • Less than 5% of cases are caused by a problem in the brain or pituitary gland.
  • In the developing world, most cases of congenital hypothyroidism are due to iodine deficiency in the mother and the baby.



What Are the Symptoms of Hypothyroidism in Infants and Children?

The signs and symptoms of hypothyroidism vary depending on the age of the child.

Symptoms In Infants And Young Children

Hypothyroidism that occurs in infancy or early childhood is called cretinism. Babies born with hypothyroidism classically show a number of symptoms in the first weeks to months of life. At birth, many symptoms are subtle, though, and can be missed. They include the following:

  • Prolonged newborn jaundice (a yellow discoloration of the skin and the whites of the eyes)
  • Poor feeding and constipation
  • Cool, mottled skin
  • Increased sleepiness
  • Decreased crying
  • Larger-than-normal soft spots on the skull
  • Umbilical hernia (a soft protrusion around the navel)
  • A large tongue

Over time, if untreated, other symptoms typically become apparent in older infants, toddlers, and young children. The most obvious symptoms observed in these youngsters reflect insufficient thyroid hormone for growth and development:

  • Short stature for age and delayed eruption of baby teeth
  • Delays in major developmental milestones
  • Puffy facial features
  • Severe mental retardation
  • Protruding abdomen and umbilical hernia (a soft protrusion around the navel)
  • Dry skin and sparse hair

Symptoms In Older Children

When hypothyroidism develops in older children before growth and development are complete, they may have a shorter-than-average height. Puberty may be delayed. They also may have symptoms more like those found in adults:

  • Slow heart rate
  • Tiredness
  • Inability to tolerate cold
  • Dry, flaky skin
  • Puffiness in the face, especially around the eyes
  • Impaired memory and difficulty in thinking (which may appear as a new learning disability)
  • Emotional depression
  • Drowsiness, even after sleeping through the night
  • Heavy or irregular menstrual periods (in girls at the age of puberty)
  • Constipation

Think of the child’s body as a motorcar. These symptoms reflect a vehicle running at too slow a speed. Some symptoms, such as inability to tolerate cold environments, are directly due to the decrease in heat generated within the body by slowed metabolic activity. Other symptoms, such as slow heart rate, tiredness, poor memory or difficulty in thinking, and even constipation, occur because there is not enough thyroid hormone to adequately stimulate  organs.


Is Hypothyroidism In Children Serious?

Normal levels of thyroid hormone are vital for proper growth and development.

Consequently, hypothyroidism, especially in infants and young children, can lead to serious, sometimes permanent, developmental problems if not detected and treated promptly.

For infants born with hypothyroidism, diagnosis and treatment within the first month or so of life may prevent any irreversible problems with the child’s development.

On the other hand, if diagnosis or treatment is delayed until after the first two or three months of life, permanent problems with the child’s development, most noticeably mental retardation, may be unavoidable.

The older the child when hypothyroidism develops, the less the chances of permanent effects on the child. Consequently, older children who develop hypothyroidism may show many of the symptoms associated with inadequate organ stimulation (such as slowed heart rate, difficulties in thinking and learning, and constipation) but little, if any, permanent abnormality in growth or development.


How Is Hypothyroidism Diagnosed in Infants and Children?

In the United States, Canada, and much of the Western world, newborns are routinely screened for thyroid hormone deficiency. Infants with abnormal screening tests receive follow-up evaluation for hypothyroidism. Such testing commonly leads to the correct diagnosis within the first four weeks of age, and treatment can begin immediately.

Diagnosis later in childhood is usually based on information from blood tests, which check levels of thyroid hormones T4, T3, and TSH, among other related substances. Abnormally low levels of T4 and T3 indicate hypothyroidism is present.

  • If TSH is present at a higher-than-normal level, the abnormality is within the thyroid gland. It is not responding properly to TSH.
  • If TSH is low, the abnormality is within the brain or pituitary gland. The pituitary is not releasing TSH despite levels of thyroid hormone low enough that it should do so.

Among babies with hypothyroidism, roughly 95% or more of cases represent problems in the thyroid gland. In less than 5% of cases, the abnormality is found in the brain or in the pituitary gland, the small gland at the base of the brain, almost always the pituitary gland.

This is the same for hypothyroidism that develops in older children and young adults, although the exact causes of hypothyroidism are different for the different age groups.

For more about diagnosis of hypothyroidism in general, see How is Hypothyroidism Diagnosed?


What Causes Hypothyroidism in Infants and Children?

The vast majority of cases of childhood hypothyroidism (95% or more) are caused by a problem within the thyroid gland or by lack of a thyroid gland. A much smaller number of cases (less than 5%) are caused by a problem in the brain or pituitary gland, the small gland at the base of the brain that releases the hormone that stimulates the thyroid gland to produce thyroid hormone.

Specific causes of hypothyroidism vary for different age groups.

Causes Of Hypothyroidism In Newborns

Hypothyroidism present from birth is called congenital hypothyroidism (congenital means at birth), or CH. In North America, CH is found in roughly 1 in every 4,000 newborns. Three causes of CH result in permanent hypothyroidism and require life-long treatment, and these account for about 90% of all newborns with CH:

  • Abnormal thyroid gland development includes babies born without a thyroid gland and those whose thyroid is not functioning (roughly 80% to 85% of cases).
  • Abnormal thyroid hormone production is much less common (roughly 10% to 15% of cases). It is often inherited. In the typical instance, both parents have normal thyroid function but are carriers for the defective gene. In such cases, the odds are one in four for each pregnancy that the baby will have CH.
  • Abnormal development of the brain or pituitary gland is the least common cause of permanent CH (fewer than 5% of cases). Some of these rare conditions are inherited, whereas others show no familial pattern. In all of these cases, TSH is not produced or released, and the resultant hypothyroidism is due to lack of thyroid gland stimulation.

About 10% of newborns with CH have a temporary hypothyroidism that will resolve within days or months, depending on the specific cause. In almost all of these cases, the hypothyroidism is due to antithyroid substances that crossed from the mother’s bloodstream into the unborn baby’s blood.

In rare cases, if the mother has Graves’ disease, an autoimmune disorder affecting the thyroid gland in which too much thyroid hormone is produced, a thyroid-blocking antibody may cross from the mother’s bloodstream into the baby’s blood. This causes the baby’s thyroid gland to temporarily stop producing thyroid hormone. More commonly, the antithyroid drug being taken by the mother for the treatment of her hyperthyroidism, affects the normal functioning of the baby’s thyroid gland.

Causes Of Hypothyroidism That Develops During Childhood

Hypothyroidism that develops during childhood has a number of causes. In general, the older the child, the more likely it is that the cause will be similar to the causes of hypothyroidism in adults.

Causes of hypothyroidism that develops during childhood include:

  • Late appearance of a congenital problem – A congenital problem is a problem with which a baby is born. But sometimes these problems may only become apparent later, after the newborn period. These children may have small or poorly formed thyroid glands that could not meet the demands of the growing child.
  • Inhibition of thyroid hormone production in the thyroid gland –Inability to produce enough thyroid hormone may reflect poor function of an apparently normal thyroid gland. In many cases, a cause is eventually determined, such as too little iodine in the diet or drug side effect. Fortunately, iodine deficiency does not exist in North America, but it continues to be a major public health problem in other, less developed areas of the world.

Some drugs intended for a nonthyroid condition can cause hypothyroidism by inhibiting production of thyroid hormone. These include lithium (used for psychiatric disorders) and iodine-containing drugs such as amiodarone (used for heart disorders).

In older children especially, antithyroid drugs used to treat those who have hyperthyroidism can actually cause hypothyroidism. This happens when the drugs inhibit hormone production too much, and the child moves from having an overactive thyroid gland to having an underactive one.

In virtually all cases, drug-related hypothyroidism is reversible. If the dosage of the drug is lowered or the drug discontinued, the hypothyroidism will disappear. In some cases, however, there may not be a reasonable alternative drug, and it becomes simpler to treat the hypothyroidism with thyroid hormone and having the child remain on the original, hypothyroidism-causing drug.

  • Permanent thyroid cell loss as a consequence of a medical treatment – A permanent loss of functional thyroid tissue may develop after treatment of hyperthyroidism with either radioactive iodine or surgery (the latter is more commonly used in children with severe or unresponsive hyperthyroidism). It may also develop after radiation therapy for cancers of the neck or chest, such as lymphomas or Hodgkin’s disease.
  • Autoimmune disease – Autoimmune disorders are the most common cause of thyroid problems.

The immune system is a complex network that normally defends the body against “invading” organisms and other foreign substances. When the immune system detects a foreign substance in the body, it responds to this by producing antibodies against the invaders. These antibodies will recognize and attack this foreign substance when they next encounter

An immune disorder is one in which the immune system mistakenly directs an immune “attack” against its own healthy cells. Antibodies are manufactured and misdirected against some of the body’s own cells. Any condition in which the body’s immune system attacks its own cells is called an autoimmune disease.

Specifically, the immune system makes antibodies (or attack proteins) that can affect the function of the thyroid. In Hashimoto’s thyroiditis, the antibodies directly attack and destroy thyroid cells.

In Graves’ disease, these antibodies mimic the action of TSH on thyroid cells. The antibodies act like a switch put into a permanent “on” position. Thyroid cells are continually stimulated to produce and release thyroid hormone, even after blood levels become excessive.

Need To Know:

Parents should check for a family history of autoimmune disorders and thyroid disease, especially Graves’ disease or Hashimoto’s thyroiditis, and tell their child’s endocrinologist at the first visit. It is also critically important for mothers to tell their child’s doctor about any history of thyroid trouble in themselves, especially Graves’ disease or Hashomoto’s thyroiditis.

  • Problems outside the thyroid gland – Hypothyroidism can develop due to a problem in a nonthyroid part of the endocrine system (namely the brain or pituitary gland). This type of hypothyroidism, which does not originate in the thyroid gland, is much less common (perhaps 5% of cases). Almost all of these cases are due to failure of the pituitary gland to produce or release TSH.

For more about underlying causes of low thyroid hormone levels, see What Causes Hypothyroidism?


What Is The Treatment For Hypothyroidism in Infants and Children?

The treatment for hypothyroidism is simple: Supply the body with the thyroid hormone that isn’t being produced and released by the thyroid gland. Synthetic (artificially produced) thyroid hormone (T4) is manufactured in a wide range of strengths so that dosage can be individually tailored for each person.

It is important that an experienced physician oversee treatment, because the body’s need for thyroid hormone varies over the course of childhood and puberty. A child will usually be started on a daily dose of thyroid hormone, have it adjusted until a healthy level of hormone in the blood is reached, and then be monitored with regular blood tests.

Almost all children with hypothyroidism will require thyroid hormone replacement therapy for the rest of their lives. Fortunately, thyroid hormone is simple to take, and the success of therapy is easily monitored by blood tests for T4 and TSH that can be done throughout adulthood.

For more information about hypothyroidism, go to Hypothyroidism.


Living with Hypothyroidism in Infants and Children

Hypothyroidism is a common endocrine condition in adults and a relatively common endocrine condition in infants and children. This thyroid problem can be treated relatively easily and inexpensively with a daily dose of synthetic (artificially manufactured) thyroid hormone.

Thyroid treatment supplies the hormone missing in the body. Organs return to a proper level of stimulation and the child’s body can resume growth and development. In many cases, symptoms that had been distressing improve or disappear after hormone therapy has been begun.

However, if growth or organ development has been delayed due to severe hypothyroidism, the changes may be lifelong. In some of these cases, developmental problems that occurred before treatment was begun cannot be reversed. These problems include mental retardation, shortened body stature, or both.

Need To Know:

Parents and older children should be aware of the symptoms of both hypothyroidism and hyperthyroidism so that they can alert their doctors if symptoms begin to appear.

  • Symptoms of hypothyroidism occur when the body’s need for thyroid hormone increases, and the previously correct dose becomes inadequate. This is the most likely thing to happen among young children who are actively growing and among older children entering puberty. Changes that the individual might notice include feelings of fatigue, new learning problems in school, a slowed heartbeat, intolerance of cold, and constipation.
  • Symptoms of hyperthyroidism occur when the body’s need for thyroid hormone decreases, and the previously correct dose becomes excessive. Changes that the individual might notice include a feeling of nervousness, a rapid heartbeat, intolerance of hot environments, and diarrhea.

Older children should learn that treatment for hypothyroidism becomes easier as they move into adulthood. After the growth and development of childhood and puberty end, most adults enter a long phase of life when their thyroid hormone needs remain relatively stable. Thyroid hormone status does not need to be monitored as frequently, and the individual becomes more able to live life without thinking about the hypothyroidism.


Hypothyroidism in Infants and Children: Frequently Asked Questions

Here are some frequently asked questions related to hypothyroidism in children.

Q: Our daughter was recently diagnosed with hypothyroidism. She was late entering puberty (all of her friends had had menstrual periods for awhile but she didn’t) and she had begun to have real problems at school. She had also complained she always felt cold. I didn’t realize those things could mean you had something serious going on. Should I have had her see a doctor sooner?

A: Don’t feel bad. Many of the symptoms of hypothyroidism found in older children and adults are subtle and appreciated far more with hindsight after the hypothyroidism is diagnosed. It’s good your daughter’s condition was diagnosed and that she began treatment. Many of the symptoms that bother her will improve markedly or disappear after she has taken thyroid hormone for several months.

Q: I was confused when I asked my doctor about my child’s thyroid hormone level and she talked about T3 and T4 values. What do these have to do with thyroid hormone?

A: Two slightly different forms of thyroid hormone are found in the blood. One is abbreviated as T3 (thyroid hormone with 3 attached iodines) and the other as T4 (thyroid hormone with 4 attached iodines). Both are considered as thyroid hormone. The form of thyroid hormone found in replacement tablets is T4. The body naturally converts T4 into T3.

Q: The doctor said my son’s hypothyroidism isn’t due to a problem in the thyroid gland, but instead something wrong in another gland, one in his head. What does that mean?

A: Although the vast majority of cases of childhood hypothyroidism result from a problem in the thyroid gland, about 5% of cases are due to a problem in the pituitary gland. This tiny endocrine gland located under brain tissue produces and releases the hormone TSH, which stimulates the thyroid gland to produce thyroid hormone. In your son’s case, his thyroid gland isn’t making enough thyroid hormone because it isn’t receiving enough TSH to stimulate it to do so. Treatment is the same as for any other case of hypothyroidism: replacement of the missing thyroid hormone with synthetic hormone taken in tablet form.

Q: I was diagnosed with Graves’ disease in my late 20s. I took an antithyroid medicine to control my hyperthyroidism during pregnancy. When my daughter was born, she had hypothyroidism, but it was mild and went away when she was a baby. Now she is in her early 30s, and she was just diagnosed withHashimoto’s thyroiditis and hypothyroidism. Are these things related?

A: Your daughter’s temporary bout with hypothyroidism in infancy was probably due to the medication that you took for your hyperthyroidism, and that is not directly related to her developing Hashimoto’s thyroiditis. However, there is a genetic factor in developing both Graves’ disease and Hashimoto’s thyroiditis, and there is often a familial tendency toward both thyroid disorders. Individuals with Graves’ disease are at higher risk to develop Hashimoto’s thyroiditis, and persons with Hashimoto’s thyroiditis are at higher risk to develop Graves’ disease. You and your daughter can discuss this with your doctors and have any remaining questions answered.

Q: We adopted a baby from another country and brought him home when he was about four months old. Our pediatrician sent us to an endocrinologist, and he says our little boy has hypothyroidism. He also used the terms congenital hypothyroidism and cretinism. What do those terms mean?

A: Congenital hypothyroidism is hypothyroidism that is present at birth. You may see it abbreviated as CH. Cretinism is a term for hypothyroidism that appears in infancy or early childhood. Neither term is associated with any specific cause of hypothyroidism. The doctor will determine what is the cause of the hypothyroidism. You will begin to feel better as you learn more about the particulars of your son’s condition and as he begins to respond to thyroid hormone treatment.

Q: Our 3-year-old daughter was just diagnosed with hypothyroidism that her doctor says is due to defective development of the thyroid gland before birth. She was right on target developmentally until this past year. Why would something that was wrong at birth take so long to show up?

A: You should raise this question with her doctor to get the specifics of her case. Doctors do know that some infants are born with thyroid glands that are not capable of producing much thyroid hormone. Sometimes these children develop hypothyroidism when they have grown up enough that their bodies’ needs for thyroid hormone exceed the amount that the gland can make. This may be the cause of your daughter’s condition. Fortunately, thyroid hormone treatment is simple and will replace the thyroid hormone that her gland cannot make.


Hypothyroidism in Infants and Children: Putting It All Together

Here is a summary of the important facts and information related to hypothyroidism in children.

  • Hypothyroidism is the condition marked by too little thyroid hormone in the blood. Growth and development are slowed, and children have symptoms due to inadequate stimulation of organs by thyroid hormone.
  • Hypothyroidism can occur at any age, from birth well into the senior years.
  • Correct levels of thyroid hormone are necessary for proper growth and development.
  • Newborns with hypothyroidism have symptoms that reflect delays in prenatal development (such as larger-than-normal soft spots on the skull) and symptoms due to inadequate organ stimulation (such as sleepiness and constipation).
  • Small children also may have symptoms that reflect slowed development (short stature for age and mental retardation) and inadequate organ stimulation.
  • Symptoms in older children usually reflect inadequate organ stimulation (dry skin, inability to tolerate the cold, and difficulty learning).
  • The seriousness of hypothyroidism in any given child usually relates to the age at which hypothyroidism developed and the delay (if any) in beginning treatment.
  • Diagnosis is always through blood testing, which detects the abnormally low thyroid hormone levels.
  • Congenital hypothyroidism (hypothyroidism present at birth) can be temporary or permanent.
  • Hypothyroidism can result from a diet too low in iodine, the use of certain drugs, as a side effect of radiation therapy, as a result of treatment for hyperthyroidism, or from an autoimmune disorder. A small percentage of hypothyroidism cases are due to problems in the brain or pituitary gland.
  • Hypothyroidism is treated with daily doses of synthetic (artificially manufactured) thyroid hormone that replaces the hormone missing in the body.
  • Regular monitoring via blood testing provides the means for ensuring appropriate hormone replacement therapy.
  • Thyroid hormone treatment may be needed for life, but fortunately treatment is simple, inexpensive, and easily monitored.

Hypothyroidism in Infants and Children: Glossary

Here are definitions of medical terms related to hypothyroidism in children.

Adam’s apple: This part of the cartilage that forms the larynx, or voice box, can be felt at the front of the neck. It is more prominent visually and by touch in men than in women.

Antibody: A protein made by the body’s immune system to defend the body against a foreign substance like a virus, bacterium, or other foreign body, most often a foreign protein. Rarely, the body’s immune system may mistakenly make antibodies against a part of the person’s own body. This is an abnormal or autoimmune response.

Antithyroid drug: Any one of several agents used to treat hyperthyroidism that hinders production of thyroid hormone within the thyroid gland.

Autoimmune disorder: An autoimmune disorder is one in which the body’s immune system mistakenly “attacks” its own healthy tissue.

Congenital: A term meaning ‘present at birth.’

Cretinism: A general term for hypothyroidism that occurs in infants.

Endocrine gland: A gland that releases a chemical messenger, known as a hormone, directly into the bloodstream, that will affect other parts of the body. The thyroid is an endocrine gland.

Endocrinology: The subspecialty within the field of internal medicine devoted to disorders of the endocrine glands; the specialist is called an endocrinologist.

Gene: The structure within a cell’s nucleus that carries inheritable information from one generation to the next.

Graves’ disease: An autoimmune disorder in which the immune system attacks the cells of the thyroid gland causing hyperthyroidism. Hyperthyroid eye changes and skin changes are sometimes associated with it.

Growth hormone: A chemical substance produced in the pituitary gland that, along with thyroid hormone, supports proper growth and development during childhood.

Hashimoto’s thyroiditis: An autoimmune disorder of the thyroid gland in which the body’s immune system attacks the thyroid gland, destroying the cells of the thyroid gland

Hormone: A chemical substance that is produced by an endocrine gland and released into the bloodstream to have its effect on other parts of the body. Also known as a “chemical messenger”. For example, thyroid hormone, released by the thyroid gland speeds up or stimulates certain bodily functions.

Hyperthyroidism: Condition in which too much thyroid hormone is circulating throughout the body, causing excessive stimulation of metabolic activity in body cells. Same condition as thyrotoxicosis.

Hypothyroidism: Condition in which too little thyroid hormone is circulating throughout the body, causing inadequate stimulation of metabolic activity in body cells.

Immune system: The body system (consisting primarily of white blood cells) that enables the body to fight infection or reject organs from another individual.

Iodine: A chemical element found naturally in seawater and in many foods that is needed to produce thyroid hormone. Iodized table salt has had iodine added to it.

Lymphoma: Any one of several cancers (including Hodgkin’s disease) that originate in lymph nodes.

Metabolism: The chemical and physical processes in the body that create the substances and generate the energy needed for cells to function, grow normally, and divide. Metabolism is also known as metabolic activity.

Nucleus: The part of the cell that contains genes, the biological form of information that is inherited from one generation to the next and that controls cell activity.

Pituitary gland: A relatively small endocrine gland about the size of a pea. This gland is located underneath the brain and releases a number of essential hormones, including thyroid stimulating hormone (TSH).

Placenta: The structure within the pregnant uterus that is the interface between the maternal and fetal bloodstreams. Oxygen, food substances, and other materials pass from the mother’s bloodstream to the fetus’s bloodstream through the placenta.

Puberty: The last growth phase of childhood, puberty is the period during which a child’s body becomes sexually mature and develops into adult form.

Radioactive iodine: A radioactive form of iodine, which means it emits intense energy due to chemical reactions in the atomic nucleus. It is often used in the treatment of hyperthyroidism in adults and less commonly used in young children.

Synthetic thyroid hormone: Thyroid hormone (T4) that is artificially manufactured but is structurally identical to that naturally produced in the body.

Thyroid gland: Small, butterfly-shaped organ, located in the neck below and in front of the Adam’s apple, which produces thyroid hormone.

Thyroid hormone: Chemical substance produced by the thyroid gland and released into the bloodstream. It interacts with almost all body cells, causing them to increase their metabolic activity. Two forms of thyroid hormone, abbreviated as T3 and T4, are found in blood.

Thyroid-stimulating hormone (TSH): Hormone produced by the pituitary gland that interacts with thyroid cells causing them to produce and release more thyroid hormone into the blood.


Hypothyroidism In Children: Additional Sources Of Information

Here are some reliable sources that can provide more information on hypothyroidism in children.

A number of organizations offer information, support, and advocacy for persons with thyroid diseases including hyperthyroidism and hypothyroidism. They include the following:

Thyroid Foundation of America (TFA) 
Phone: 800-832-8321

American Thyroid Association



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