What is hyperthyroidism?

Hyperthyroidism, also known as hyperthyroid or overactive thyroid, occurs when the thyroid gland makes too much thyroxine, the hormone responsible for managing metabolism. Excess thyroid hormone increases metabolism and can cause weight loss, sweating and a rapid heart beat. It can also affect your child’s mood, making them nervous, irritable and anxious.

Hyperthyroidism affects many cells and tissues throughout the body, including the brain, heart, bone, skin and intestinal tract. In infants younger than 3, too much thyroid hormone can result in cognitive delay.

Hyperthyroidism is relatively rare in children and adolescents. Approximately 1 in 10,000 children have hyperthyroidism.

In newborns, the most common cause of an overactive thyroid is neonatal Graves’ disease, a temporary condition that affects girls and boys in equal numbers.

In older children, the most common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder in which a child’s immune system attacks the thyroid gland and causes it to produce an unlimited amount of thyroxine. Girls are more likely than boys to develop Graves’ disease.

With the right diagnosis and management, hyperthyroidism is a very treatable disease, and your child can go on to live a full, active and enjoyable life.

What is the thyroid gland? How does it work?

The thyroid is a small, butterfly-shaped gland in the neck that helps regulate how quickly or slowly the body uses energy.

The thyroid helps regulate metabolism through the production of thyroxine, or T4. This hormone also plays an important role in the normal growth and brain development of children. Levels of T4 are in turn regulated by thyroid-stimulating hormone (TSH), which is produced in the brain. If the T4 level is too low, TSH sends a message to the thyroid gland to make more T4.

What are the symptoms of hyperthyroidism?

The most common signs and symptoms of hyperthyroidism are:

  • difficulty gaining weight
  • fast or irregular heartbeat
  • high blood pressure
  • nervousness and trouble concentrating
  • irritability
  • bulging eyes
  • diarrhea
  • poor school performance
  • infants may have trouble breathing (caused by an enlarged thyroid gland pressing on the windpipe)

What is thyroid storm?

Thyroid storm, or thyrotoxic crisis, is a very serious complication of hyperthyroidism. It occurs when a child’s thyroid hormone levels become severely elevated. Though thyroid storm is rare, when it does occur, it can be life threatening. The most important symptom to look out for is a very high temperature (up to 105 or 106 degrees Fahrenheit). If you suspect your child may be experiencing thyroid storm, you should always seek immediate medical care.

What causes hyperthyroidism?

There are several possible causes for hyperthyroidism:

Graves’ disease, the most common cause of hyperthyroidism in children and adolescents. This is an autoimmune disorder in which the body produces antibodies that stimulate the thyroid gland to produce too much hormone.

Neonatal Graves’ disease, the most common cause of hyperthyroidism in newborns. This happens after the mother passes the thyroid-stimulating antibodies to her child, causing the baby to have a temporary case of hyperthyroidism.

Thyroid nodules, , growths in the thyroid gland that sometimes produce thyroid hormones that can lead to hyperthyroidism.

Thyroiditis occurs when the thyroid gland becomes inflamed and excess thyroid hormone leaks into the blood. This condition is rare in children.

Does hyperthyroidism run in families?

Graves’ disease is a genetic autoimmune disorder, meaning that genes play a role in the onset of the disease. If your child has been diagnosed with Graves’ disease, you and other members of your family should have your thyroid levels checked as a precaution.

If your child has an overactive thyroid caused by a nodule or thyroiditis, it is unlikely other members of your family—including siblings—will have hyperthyroidism.

How we care for hyperthyroidism

The Thyroid Center at Boston Children's Hospital is one of the first and largest centers in the United States devoted exclusively to the care of children with thyroid disease. Our clinicians and staff are involved in numerous studies about the various aspects of thyroid disease and thyroid function in childhood.

Our program is distinguished by our expertise in:

  • thyroid ultrasound, a safe and painless method of imaging that helps doctors determine the size and characteristics of thyroid nodules.
  • ultrasound-guided fine needle aspiration, a very safe, minor procedure that can usually be done in place of a major surgical biopsy. Our Thyroid Program physicians have performed more than 850 of these procedures in children.
  • radioactive iodine therapy for hyperthyroidism and thyroid cancer; this therapy—given either in a capsule or in a tasteless solution in water—makes use of the thyroid gland’s natural need for iodine to treat overactive or cancerous thyroid cells.

We work closely with other thyroid specialists across the greater Boston area, including experts at Brigham and Women’s Hospital and Dana-Farber Cancer Institute.