Hyperthyroidism

In hyperthyroidism, the thyroid gland makes too much thyroid hormone. An overactive thyroid gland pushes the body’s metabolism to unhealthy levels. This bow tie-shaped gland in the throat, at the bottom of the neck, wraps around the windpipe (trachea), near nerves important to the voice.

Hyperthyroidism's Effects

The thyroid hormone affects almost every tissue and cell in the body and controls many metabolic processes. The hormone influences physical growth, energy and mental development. When the gland sends out too much thyroid hormone, the body’s processes speed up, affecting:

• Brain development
• Breathing
• Heart and nervous system functions
• Body temperature
• Muscle strength
• Skin dryness
• Menstrual cycles
• Weight
• Cholesterol

In children, hyperthyroidism can affect growth, puberty development and the bones.

Hyperthyroidism is very rare in a baby. A newborn boy or girl may have trouble breathing if the thyroid gland is enlarged and pressing on the windpipe. The main signs are failure to thrive and gain weight, even though the baby has an enormous appetite.

Untreated hyperthyroidism can lead to heart problems, including rhythm disturbances. If it isn’t detected for a long time, it can weaken the bones. If a newborn with hyperthyroidism isn’t treated, the condition can affect the growth and development of the nervous system.

What Causes Hyperthyroidism?

Graves’ disease

Almost all cases of hypothyroidism in children and teens are caused by the autoimmune disease known as Graves’ disease. Among children, we see hyperthyroidism most often in adolescent girls. It may come and go throughout life, needing treatment for months or years at a time and then not needing treatment for some time.

Other Rare Causes

Thyroid nodules, inflammation of the thyroid (thyroiditis), consuming too much iodine and overmedicating with synthetic thyroid hormone (the treatment for underactive thyroid) are far less common causes of hyperthyroidism in children. With thyroiditis, hyperthyroidism lasts about six to eight weeks instead of two to three years.

Cause in Newborns

Hyperthyroidism in newborns occurs only when a thyroid-stimulating antibody passed through the placenta from a mother who has or had Graves’ disease. In newborns, hyperthyroidism is temporary (transient) and requires medication for just a few months.

The condition is very treatable. The endocrinologist starts the child on oral medication and carefully adjusts the doses. Anti-thyroid medication, thyroidectomy (surgery to remove the thyroid gland) and radioactive iodine ablation (to destroy the gland) can also be used to treat the condition.

What Are the Symptoms of Hyperthyroidism?

Newborns

• Mother has or had Graves’ disease
• Rapid heart beat
• Enlarged thyroid gland (goiter)
• Irritable
• Poor weight gain
• Bulging eyes (seem to be staring)

Children & Teens

• Increased energy or hyperactivity
• Irritability, nervousness or anxiety
• Poor weight gain or weight loss
• Hand tremor
• Fast heartbeat
• High blood pressure
• Bulging eyes (the child seems to stare)
• Diarrhea
• Enlarged thyroid gland

How Is Hyperthyroidism Diagnosed?

At your first visit, the endocrinologist will get your child’s medical history, do a physical exam and decide 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 thyroid disease (Graves’ or Hashimoto’s)? The doctor feels around the neck, carefully checking the thyroid gland. Is it swollen (a lump or goiter)? Are there nodules?
• Blood tests: We usually test a blood sample to find out how much thyroid-stimulating hormone is in the blood. This test is very sensitive and accurate. It detects even mild hyperthyroidism.

Other tests are sometimes needed to confirm the diagnosis, find the cause or guide treatment, such as:

• Blood tests: One blood test measures thyroxine (T4) and triiodothyronine (T3) levels. Another looks for the antibody (thyroid-stimulating immunoglobulin), which is usually seen with Graves’ disease but not with other causes.
• Radioactive thyroid tests: For these tests, the child swallows a small dose of radioactive iodine. The radioactive iodine uptake test finds problems with how the thyroid gland works. A thyroid scan shows if the entire thyroid gland is overproducing or just part of it. The scan also shows any nodules or enlargement of the thyroid gland.

The diagnosis can quickly be confirmed in newborns.

How Is Hyperthyroidism Treated?

Treatment varies based on the child’s age and other medical conditions. Hyperthyroidism can be treated in three ways:

• Anti-thyroid medication: Pills taken on an ongoing, daily basis
• Thyroidectomy: A surgery to remove some or all of the thyroid gland
• Radioactive iodide ablation: A procedure that stops the thyroid from producing too much hormone

The child may be given additional medication to reduce the symptoms and must be monitored to see how the treatment is working:

• Beta-blocker: Often, this medication is added to lower the heart rate and blood pressure until the therapy takes effect. It helps with other symptoms, too, such as trembling, anxiety and overheating. The medication usually makes the child feel better within hours or days.
• Monitoring and blood tests: Throughout treatment, the child must be monitored frequently for symptoms, side effects and thyroid hormone levels.
• Treatment for newborns: In a newborn, the antibodies from the mother clear out in a few months. Until then, the baby is given anti-thyroid medication so the body functions right.

Antithyroid Medication

Typically, treatment starts with an anti-thyroid medication. The medication slows down the production of thyroid hormone. It doesn’t usually have permanent results, and it doesn’t work for thyroiditis. Methimazole is a good choice because the child may only need to take it once a day and it causes fewer liver abnormalities. Another choice is propylthioracil (PTU).

Daily Pills

Usually, the medication can be taken once or twice a day. Typically, thyroid hormone levels return to the normal range in several weeks or months. The average treatment time is about one to two years, but treatment can continue for many years if needed.

“The strongest reason we like this treatment, versus radiating the thyroid or surgically removing it, is that Graves’ disease very frequently goes into remission,” says Donald Zimmerman, MD. “Remission happens most often in milder cases. When the disease goes into remission, the child can stop treatment. We then use tests to be sure the thyroid hormone is in the normal range.”

Side Effects

Anti-thyroid medications can cause side effects in some children. Allergic reactions such as rashes and itching are common, and headaches may occur. The body has fewer white blood cells and lower resistance to infection because of the medication. Liver failure is a side effect in rare cases.

“With anti-thyroid medication, a child is more susceptible to infection. We tell families that if the child seems to be coming down with an infectious illness — for example, a sore throat or fever — they need to get the child’s white blood cell count tested,” says Dr. Zimmerman.

Surgery

A thyroidectomy removes all or part of the thyroid gland. Surgery is considered when medication doesn’t work or the child has trouble with the medication (for example, the child develops a liver abnormality). The surgery leaves a scar but eliminates the hyperthyroidism. The child takes a thyroid hormone replacement tablet once a day throughout life.

You’ll want a surgeon with specialized training and appropriate experience. The surgeon must be careful of the nerves for the vocal cords and of the parathyroid gland that regulates calcium in the blood. Lurie Children’s has personnel and technology in the operating room especially to protect the vocal nerve from injury.

Radioactive Iodide Ablation

To permanently stop hyperthyroidism, the child can be given a capsule to swallow that has a small amount of radioactive iodide. The thyroid gland absorbs most of the radioactive iodide. Over several weeks or months, the radiation destroys part or all of the gland. Some children, not many, need a second dose or may need surgery to remove the gland. If the thyroid gland then produces no thyroid hormone, the child takes a hormone replacement tablet once a day throughout life.

“We tend to use radioiodine in older adolescents, rather than younger children. We’re mindful that young people have a greater risk of radiation-induced cancer,” explains Dr. Zimmerman. “All over the world and country, there’s a push to minimize radiation, to avoid changing the genetic material.”

Review Every Option

Radioactive iodide and surgery are hospital-based treatments that offer a permanent solution to hyperthyroidism, but with increased risks. Medication is inexpensive, poses fewer risks and may eventually or at times be discontinued. Some children have trouble taking their medication on time if they have to take it more than once a day. This jeopardizes their health.

Our pediatric endocrinologists will talk with you about the plusses, minuses and appropriateness of each option in your child’s situation. We try to minimize the risks of radiation and surgery as much as possible. The goal is to return the child to wellness.

Make an Appointment

If you're concerned your child may have hyperthyroidism, you can make an appointment with one of our pediatric endocrinologists to have your child examined. To request an appointment with one of our endocrinologists, call 1.800.543.7362 (1.800.KIDS DOC®).

Resources

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

• American Thyroid Association
• Hormone Foundation
• National Endocrine and Metabolic Diseases Information Service
• The MAGIC Foundation for Children’s Growth

Recommended publications:

• The Complete Thyroid Book, 2nd Edition; A book by K. Ain and M. S. Rosenthal, McGraw Publishing, 2010