Hyperthyroidism | Symptoms & Causes
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.
Hyperthyroidism | Diagnosis & Treatments
How is hyperthyroidism diagnosed?
Diagnosing hyperthyroidism starts with a complete medical history, followed by a physical exam. To confirm a diagnosis, your child’s doctor may:
- request blood tests to check the levels of your child’s thyroid hormones and/or thyroid-stimulating antibodies (a test for Graves disease)
- perform thyroid imaging studies, such as a thyroid scan or ultrasound, to determine the size, shape, function, and position of the thyroid gland
How is hyperthyroidism treated?
Graves disease
Graves disease is the most common cause of hyperthyroidism in children and adolescents. The goal of treatment is to decrease the function of the thyroid gland back to normal so that it produces a normal amount of thyroid hormone.
There are three types of treatment for Graves disease:
- Antithyroid drugs work by blocking the thyroid gland’s ability to make thyroid hormone. These drugs do not damage the thyroid gland itself. In many patients, antithyroid drugs can maintain normal thyroid hormone levels for many years. Some patients who respond well to antithyroid drugs may eventually be able to stop taking them and remain with normal thyroid function. Antithyroid drugs are generally safe but can have rare, serious side effects, so they need careful monitoring.
- Radioactive iodine uses the thyroid gland’s natural need for iodine to treat overactive thyroid cells. Radioactive iodine is absorbed by and permanently destroys the thyroid gland, but does not affect other parts of the body. Once the thyroid gland is destroyed, the patient will need to take thyroid hormone medication.
- Surgery to remove the thyroid gland is very effective for treating Graves disease. This procedure is generally safe but rarely can have serious complications. For this reason, it is important that the procedure be performed by an experienced thyroid surgeon. Lifelong thyroid hormone medication is needed after the thyroid is removed.
Additional treatments for Graves disease may include medications to improve symptoms (like palpitations and anxiety), which can be used temporarily until thyroid hormone levels are brought down to normal by one of the three treatments above.
Neonatal Graves disease
Neonatal Graves disease is a temporary condition that lasts only until the mother’s thyroid-stimulating antibodies have been cleared from the baby’s circulation. Until the condition goes away, antithyroid drugs are used to control the baby’s overactive thyroid. With prompt treatment, babies usually recover completely within a few weeks. However, either hyperthyroidism or hypothyroidism (low thyroid function) may occur later in the first year of life, so continued monitoring by a physician is important.
Autonomous thyroid nodules
Autonomous thyroid nodules are usually benign. Their treatment depends on how much thyroid hormone they produce, and on whether this is causing symptoms of thyroid hormone excess.
- Autonomous nodules that are slightly overactive and cause no symptoms. It can often be observed without treatment.
- Nodules that are very overactive or that cause symptoms can be treated with medication, surgery, or (in patients over 18 years) radioactive iodine ablation.
Our approach to treating autonomous nodules is slightly different than that recommended by the American Thyroid Association, which recommends surgery for all autonomous nodules in children. Our approach is based on our extensive experience with this condition — which was published after the release of the American Thyroid Association guidelines — showing that with careful evaluation, some autonomous nodules can be managed safely without surgery.
Thyroiditis
Hyperthyroidism caused by thyroiditis is usually temporary and goes away within eight to 12 weeks. Because we cannot make this hyperthyroidism go away any faster, treatment focuses on medications to control any symptoms (like palpitations and anxiety) until the condition goes away on its own. Sometimes, this type of hyperthyroidism is followed by a period of hypothyroidism (low thyroid function), so continued monitoring by a physician is important.
How we care for hyperthyroidism at Boston Children’s Hospital
Our Thyroid Center 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
