Hypothyroidism in Children

In hypothyroidism, the thyroid gland is underactive and fails to make enough thyroid hormone. Hypothyroidism is common in children and adolescents and is very treatable. In newborns, a lack of thyroid hormone is serious and needs prompt treatment.

Thyroid hormone affects almost every cell in the body. When there isn’t enough thyroid hormone, the body’s processes start slowing down. Physical growth and mental development are very slow. Bones and nerves don’t develop right.

In hypothyroidism, the body’s fuels are sluggish, and therefore basic body functions — like heartbeats and speaking — are slow. Children may lack energy and have trouble concentrating. The cells are even slow to generate the body heat that keeps the child warm and comfortable. Symptoms can be subtle and confused with issues in normal life or other health conditions. Treatment (usually a pill a day) controls the condition well. Treatment is available through the specialists in the Division of Endocrinology.

What Causes Hypothyroidism?

Hypothyroidism may be present at birth (congenital) or develop later (be acquired). Giving the child medicine (the right dose of a replacement hormone) is important to prevent learning problems, allow normal physical growth and help the child feel well. Sometimes, an infant’s thyroid deficiency is mild and temporary (transient), due to exposure in the womb or iodine. More often, the medicine is used throughout life.

The bow tie-shaped thyroid gland is in the throat, at the bottom of the neck, wrapped around the trachea, near the nerves that control the vocal cords and voice box. In children, the problem is usually how the gland is working or how it’s prevented from producing thyroid hormone for the body to use.

Newborns with Congenital Hypothyroidism

Congenital hypothyroidism is very treatable, though newborns with untreated hypothyroidism are at risk for intellectual disabilities. When newborns are diagnosed and treatment starts within a few weeks of birth, growth and development are usually very normal. Some children will still have problems in school and with speech. Taking the medicine every day protects intelligence, normal growth, coordination and the heart.

Causes in Newborns

A few babies are born without a thyroid gland or with only a partially formed one. A few have part of or their entire thyroid in the wrong place. In some babies, the thyroid cells or their enzymes don’t work right. What causes congenital hypothyroidism in newborns is usually different than hypothyroidism that starts later.

  • Structure of the thyroid gland: One cause of congenital thyroiditis is an abnormally formed thyroid gland. Almost always, the reason for this cannot be determined. The gland may be of normal size.
  • Function of the thyroid gland: Sometimes, congenital hypothyroidism occurs because the thyroid gland isn’t able to make thyroid hormone. An error occurs in one of the steps. The gland enlarges into what is called a goiter.
  • Problem in the pituitary gland: Rarely, the problem is that the pituitary gland isn’t making thyroid-stimulating hormone. This “master gland” should tell the thyroid how much hormone to make. A damaged pituitary may no longer be able to instruct the thyroid, and the thyroid may stop making enough hormone.

Diagnosis in Newborns

All states require that newborns have a blood test for congenital hypothyroidism. The test usually measures the amount of thyroid-stimulating hormone in the blood. Starting hormone replacement within weeks of birth makes it possible for a newborn with hypothyroidism to develop normally, free of brain damage and intellectual disabilities. Babies with hypothyroidism can look perfectly normal, so the screening test is critical. On average, Illinois’ Newborn Screening Program identifies 60 to 70 children with congenital hypothyroidism each year.

The initial test — requiring a prick of the heel to get droplets of blood — is done before the child is four or five days old (seven days at the latest if the child is premature, born at home or critically ill). Using a screening test is far better than relying on symptoms and signs because those are often mild and not noticed until the brain is damaged. Brain damage cannot be reversed.

Some symptoms in newborns:

  • Prolonged jaundice (yellowish skin)
  • Hoarse cry
  • Poor appetite, poor feeding
  • Constipation
  • Bulging naval
  • Sleepy
  • Doesn’t kick vigorously
  • Unusually large tongue

As soon as something seems wrong (in the screening test or the baby), the pediatrician needs to refer the family to a pediatric endocrinologist. A second drop of blood must be tested. After two positive tests, hypothyroidism is diagnosed. Even after normal screening tests, an infant’s health care provider may have reason to test for hypothyroidism. The disorder can develop after birth.

Treatment for Newborns

The endocrinologist sets the starting dose of hormone replacement. Sometimes, signs and symptoms aren’t seen for a few weeks, but treatment must start within weeks of the birth to prevent intellectual disabilities and brain damage. Left untreated, the condition also leads to poor coordination, shakiness and unsteadiness. Adequately replacing the hormone is important to prevent learning delays and slow growth.

  • Thyroid hormone replacement: Treatment is usually just one tablet of levothyroxine a day, taken around the same time each day. The tablet can be crushed and mixed with liquid, but not soy formula or formula containing iron. As the infant grows, the dose is increased. Older children simply chew or swallow the tablet.
  • Blood test: A baby with congenital hypothyroidism needs to have a thyroid test every two to three months during the first year.

Children & Teens with Hypothyroidism

In children and adolescents (not infants), hypothyroidism is most often caused by an inflamed thyroid gland. The inflamed gland (thyroiditis) is usually caused by an autoimmune attack or a viral infection.

Transient Hypothyroidism

Transient Hypothyroidism

Sometimes, the condition is gone a few weeks after birth. Sometimes, there’s no evidence of hypothyroidism after two to three years. The safest approach is to take the hormone replacement through the crucial time of brain development.

At a safer point in the future, the doctor may stop the medicine for a few weeks and do blood tests. If the hormone level is normal, the child continues without medicine. At this age, a child still needing hormone replacement can start the medicine again without getting brain damage during the break.

For most children, a pill a day is needed throughout life.

Hashimoto Thyroiditis

Hashimoto thyroiditis (also called chronic lymphocytic thyroiditis) is an autoimmune condition. That means the body’s immune system is attacking healthy tissue. The body is making antibodies that are gradually destroying the thyroid gland. The gland becomes chronically inflamed and may eventually fail to make enough thyroid hormone. Hashimoto thyroiditis is rare in infants. Mothers with the disorder worry that their children will be born with it, but that’s unlikely.

What Are the Effects of Hypothyroidism?

Acquired hypothyroidism affects growth and development until puberty. The child grows slowly and has less energy and appetite. Unlike the congenital disorder, the condition doesn’t permanently reduce mental function. Having one autoimmune condition makes the child more likely to develop others. In children with Hashimoto thyroiditis, we watch for other autoimmune conditions, such as arthritis, type 1 diabetes, adrenal insufficiency and vitiligo.

What Are the Symptoms of Hypothyroidism?

The most obvious symptom is that the child has stopped growing. There are seldom other symptoms to notice. The signs and symptoms vary depending on the child’s age and how much thyroid hormone is missing. They may be mild, moderate or severe. The same symptoms can be due to some other cause in the child’s body or life. The disorder may progress for years until it is diagnosed and treated.

Some Signs Symptoms of Hypothyroidism

What you notice in children:

  • Stunted growth, slow growth, no growth
  • Delayed tooth development
  • Cold intolerance; often complains of being cold

What you notice in adolescents:

  • Stunted growth, slow growth, no growth
  • Cold intolerance; often complains of being cold
  • Fatigue, little energy
  • Poor appetite
  • Slow speech
  • Slow pulse
  • Slower reaction time (can affect teen driving)
  • Depression
  • Dull facial expression
  • Droopy eyelids
  • Puffy, swollen face
  • Hoarse voice
  • Enlarged thyroid (goiter)
  • Constipation, hard stools
  • Muscle cramps, weakness
  • More menstrual cramps, heavier periods
  • Dry skin
  • Dry hair or hair loss (e.g., sides of eyebrows)
  • Generalized increase in body hair - arms, legs, back
  • Delayed puberty
  • Moderate weight gain
  • Poor performance in school

Weight Gain

Some parents and children’s doctors wonder if an overweight child has an underactive thyroid, and they consult an endocrinologist. An overweight child may have a higher TSH level (like hyperthyroidism). A child with hypothyroidism may be mildly overweight, but not significantly overweight or obese.

Hypothyroidism slows the metabolism and activity levels, but the child isn’t very hungry.

How much fat someone has greatly affects how much thyroid-stimulating hormone (TSH) they make. The TSH level is above normal in a child who is overweight, but that’s not due to an underactive thyroid, and hormone replacement won’t help. When someone has a lot of body fat, they have a lot of leptin, which stimulates the body to make TSH. A mildly high TSH level can be an effect, not the cause, of being overweight.

How Is Hypothyroidism Diagnosed?

Because the signs and symptoms can be subtle, our pediatric endocrinologist will be very thorough at your initial visit. The doctor gets the medical history, does an exam and decides if a blood test is needed.

  • History and physical examination: The doctor takes a careful history of the child and family. Have family members had an autoimmune condition? The doctor feels around the neck, carefully checking the thyroid gland. Is it swollen (a lump or goiter)? Are there nodules? Signs and symptoms that could be due to a thyroid disorder are noted and considered.
  • Blood test: We measure the levels of thyroid hormones in a sample of blood. The amounts of thyroid-stimulating hormone (TSH) and free T4 (free thyroxine) in the blood are important to learn. Testing for antithyroid antibodies is often helpful as well.

How Is Hypothyroidism Treated?

To bring the hypothyroidism under control, the doctor prescribes a daily medicine. The medicine replaces the thyroxidine (“T4”) the body isn’t making. The doctor carefully considers the right starting dosage. Treatment continues and is adjusted and monitored throughout life.

  • Steroid replacement first, if needed: The adrenal gland of a child with Hashimoto thyroiditis may also be under attack by the immune system and fail to make cortisol. This adrenal insufficiency is called Addison disease. We do a blood test make sure the body has enough cortisol before we give a thyroid hormone replacement.
  • Thyroid hormone replacement: The child starts with a small dose of levothyroxine (a synthetic replacement for the thyroid hormone). We increase the dose slowly over time. The tablet can be crushed and mixed with liquid, chewed or swallowed.

Children of the same gender, age and weight need different doses. We find the child’s “normal” level. This dose changes as the child’s height and weight change. The right dose eliminates the signs and symptoms; restores the growth rate to normal for the child’s age; and keeps the blood level of thyroid-stimulating hormone in normal range.

Adequately replacing the hormone is important to prevent learning delays and slow growth. It is important for the child to take the medicine every day.

Treatment Notes

  • Headaches: Watch for headaches; they’re signs that there’s too much spinal fluid and the dose needs to be lowered.
  • Performance in school: If the hormone replacement is too rapid, the child can have trouble paying attention in school, and the dose needs to be lowered.
  • Symptoms should go away: Very rarely, an autoimmune condition isn’t the cause of the hypothyroidism and thyroid hormone replacement isn’t the answer. If you’re concerned that your child’s symptoms aren’t going away, tell your doctor.

Check-ups Blood Tests

Your child’s ongoing care includes blood tests to make sure the dose of thyroid hormone is adequate. Check-ups by the primary care provider keep the care plan on track with the child’s growth. Hypothyroidism can lead to anemia, low body temperature and heart failure if it’s not treated. Newborns with hypothyroidism who don’t receive timely treatment become mentally disabled.
Usually, treatment is a daily thyroid hormone tablet. In follow-up visits, we see how the child is developing and growing, judge how the medicine is working and make dose adjustments. 
We work with the family to get and keep the child’s dose right. This way, the condition is fully controlled. Symptoms should disappear. The serious effects of low thyroid hormone should improve.

Caring for Your Child

Your doctor at Lurie Children’s is an excellent resource. We’ll guide you to knowledgeable specialists so your child gets timely, expert care to help with issues like speech delays. Our team in the Division of Endocrinology knows that prompt attention helps keep problems small and maximizes your child’s health.


Learn more about thyroiditis by visiting the following physician-recommended websites:

Resources on newborn screening and congenital hypothyroidism:

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