What is hyperthyroidism?

Hyperthyroidism (also known as overactive thyroid) occurs when the thyroid gland makes too much thyroid hormone (thyroxine). Hyperthyroidism is relatively rare in childhood, occurring in about 1 in 5000 children and adolescents. With the right diagnosis and management, hyperthyroidism is a treatable disease, and your child can go on to live a full, active and enjoyable life.

What causes hyperthyroidism?

There are several possible causes of hyperthyroidism.

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

Neonatal Graves disease is the most common cause of hyperthyroidism in newborns. This happens after a mother with Graves disease passes her thyroid-stimulating antibodies to her child, causing the baby to have a temporary case of hyperthyroidism. Neonatal Graves disease goes away once the mother’s antibodies are cleared from the baby’s bloodstream, usually after a few weeks.

Autonomous thyroid nodules (also called toxic or hot nodules) are growths in the thyroid gland that produce too much thyroid hormone.

Thyroiditis occurs when the thyroid gland becomes inflamed, causing too much thyroid hormone to leak out of the damaged thyroid and into the blood. Thyroiditis can be caused by infections, autoimmune conditions, radiation exposure, or certain medications. Hyperthyroidism caused by thyroiditis is temporary and usually goes away within eight to 12 weeks.

What are the symptoms of hyperthyroidism?

Thyroid hormone has important effect on almost every organ in the body, including the brain, heart, bone, skin, and intestinal tract. In hyperthyroidism, excessive amounts of thyroid hormone can cause symptoms from any of these organs. Excess thyroid hormone increases metabolism and can cause weight loss, sweating, and a rapid heartbeat. It can also affect your child’s mood and ability to concentrate, making them nervous, irritable, and anxious. In infants, too much thyroid hormone can result in developmental delay.

Signs and symptoms of hyperthyroidism may include:

  • difficulty gaining weight
  • fast or irregular heartbeat
  • high blood pressure
  • frequent bowel movements
  • warm, moist skin
  • always feeling hot (even when others are not)
  • trembling of the hand
  • nervousness
  • irritability
  • trouble concentrating
  • poor school performance
  • staring or bulging eyes
  • symptoms of thyroid enlargement, like trouble swallowing or, in infants, trouble breathing

Thyroid storm (or thyrotoxic crisis) is a serious complication of hyperthyroidism. It occurs when a child’s thyroid hormone levels become severely elevated. Although thyroid storm is rare, it can be life threatening. The most important symptoms of thyroid storm are a high temperature or changes in mental status (like confusion or lethargy). If you suspect your child may be experiencing thyroid storm, you should always seek immediate medical care.

How we care for hyperthyroidism at Boston Children’s Hospital

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 Center is distinguished by our extensive experience in:

  • Nuclear medicine imaging of the thyroid (thyroid scan) to determine the cause of hyperthyroidism;
  • Radioactive iodine therapy for hyperthyroidism — this therapy, given as a capsule or liquid, uses the thyroid gland’s natural need for iodine to treat overactive thyroid cells;
  • Surgery for hyperthyroidism (including Graves disease and autonomous thyroid nodules), when appropriate.