Graves disease is the usual cause of hyperthyroidism, but growths (nodules) on or inflammation of the thyroid gland, drugs, and infections can be causes too.
Symptoms depend on the child's age but typically include speeding up of bodily functions.
The diagnosis is based on blood tests and imaging tests.
Infants who are not treated until birth may have intellectual disability, growth failure, and short stature, and some may die.
Treatment typically includes antithyroid drugs and beta-blockers.
(See also Hyperthyroidism Hyperthyroidism Hyperthyroidism is overactivity of the thyroid gland that leads to high levels of thyroid hormones and speeding up of vital body functions. Graves disease is the most common cause of hyperthyroidism... read more in adults.)
The thyroid gland is an endocrine gland Endocrine Glands The endocrine system consists of a group of glands and organs that regulate and control various body functions by producing and secreting hormones. Hormones are chemical substances that affect... read more located in the neck. Endocrine glands secrete hormones into the bloodstream. Hormones Endocrine Function The main function of endocrine glands is to secrete hormones directly into the bloodstream. Hormones are chemical substances that affect the activity of another part of the body (target site)... read more are chemical messengers that affect the activity of another part of the body.
The thyroid gland secretes thyroid hormone. Thyroid hormone controls the speed of the body's metabolism, including how fast the heart beats and how the body regulates temperature. If the thyroid gland produces too much thyroid hormone, these functions speed up.
Locating the Thyroid Gland
Hyperthyroidism can occur in a developing fetus or infant (see Hyperthyroidism in the Newborn Hyperthyroidism in the Newborn Hyperthyroidism is increased production of thyroid hormone. Hyperthyroidism in the newborn is usually caused by Graves disease in the mother. Symptoms include irritability, rapid heart rate... read more ) or during childhood or adolescence.
Hyperthyroidism is rare in infants but can be life-threatening. It develops in fetuses of women who have or have had Graves disease Graves disease Thyroid disorders may be present before women become pregnant, or they may develop during pregnancy. Being pregnant does not change the symptoms of thyroid disorders. How the fetus is affected... read more . In Graves disease, abnormal antibodies stimulate the thyroid gland to produce excess thyroid hormone. These antibodies may cross the placenta and stimulate the thyroid gland in the fetus, which may cause premature birth or even death. Because infants are no longer exposed to the mother's antibodies after birth, Graves disease in the newborn (neonatal Graves disease) is usually temporary, but the duration varies.
Children and adolescents
The cause of hyperthyroidism in more than 90% of children and adolescents is Graves disease Graves disease Hyperthyroidism is overactivity of the thyroid gland that leads to high levels of thyroid hormones and speeding up of vital body functions. Graves disease is the most common cause of hyperthyroidism... read more .
Less common causes include growths (nodules) on the thyroid gland, inflammation of the thyroid gland (Hashimoto thyroiditis Hashimoto Thyroiditis Hashimoto thyroiditis is chronic, autoimmune inflammation of the thyroid. Hashimoto thyroiditis results when the body attacks the cells of the thyroid gland—an autoimmune reaction. At first... read more , in which hyperthyroidism is temporary and children eventually develop hypothyroidism Hypothyroidism in Infants and Children Hypothyroidism is decreased production of thyroid hormone. Hypothyroidism in children usually occurs when there is a structural problem with the thyroid gland or the thyroid gland is inflamed... read more ), and some drugs. Occasionally, temporary hyperthyroidism can be caused by infections, including bacterial (acute thyroiditis) and viral (subacute thyroiditis Subacute Thyroiditis Subacute thyroiditis is acute inflammation of the thyroid, probably caused by a virus. (See also Overview of the Thyroid Gland.) Subacute thyroiditis usually begins suddenly. In this disorder... read more ) infections.
Symptoms of hyperthyroidism differ depending on the age of the child.
Symptoms of hyperthyroidism in fetuses may appear as early as the second trimester. Affected fetuses have poor growth, a very fast heart rate, and an enlarged thyroid gland (goiter Congenital Goiter Congenital goiter is enlargement of the thyroid gland that is present at birth. The enlarged thyroid gland may produce too much thyroid hormone (hyperthyroidism), too little thyroid hormone... read more ). If the disorder is present and untreated for a long period before birth, about 10 to 15% of infants die and others have impaired intellectual development Intellectual Disability Intellectual disability is significantly below average intellectual functioning present from birth or early infancy, causing limitations in the ability to conduct normal activities of daily... read more , poor growth, and short stature.
In infants, symptoms include irritability, feeding problems, high blood pressure, fast heart rate, bulging eyes, congenital goiter Congenital Goiter Congenital goiter is enlargement of the thyroid gland that is present at birth. The enlarged thyroid gland may produce too much thyroid hormone (hyperthyroidism), too little thyroid hormone... read more , and skull abnormalities. Other symptoms include failure to thrive Failure to Thrive Failure to thrive is a delay in weight gain and physical growth that can lead to delays in development and maturation. Medical disorders and a lack of proper nutrition are causes of failure... read more , vomiting, and diarrhea.
Older children and adolescents
Symptoms of hyperthyroidism reflect the speeding up of bodily functions:
Increased heart rate and blood pressure
Frequent bowel movements
Although bodily functions increase, concentration and school performance decrease. Goiter may be present. Children may have red or bulging eyes.
Symptoms of acute thyroiditis develop suddenly. Children have tenderness over the thyroid gland, and fever. In subacute thyroiditis, these symptoms are present but are less severe and may begin after a viral illness. Fever may last for several weeks.
Complications of hyperthyroidism
Thyroid storm Thyroid storm Hyperthyroidism is overactivity of the thyroid gland that leads to high levels of thyroid hormones and speeding up of vital body functions. Graves disease is the most common cause of hyperthyroidism... read more is a rare, severe complication of hyperthyroidism and a life-threatening emergency. In thyroid storm, the thyroid gland becomes suddenly and extremely active. All body functions are accelerated to dangerously high levels. Symptoms in affected children include an extremely fast heart rate, high body temperature, high blood pressure, heart failure, and changes in mental status. This disorder can lead to coma and death.
Thyroid function tests
Sometimes imaging tests
In infants, doctors suspect the diagnosis of hyperthyroidism if the mother has active Graves disease or a history of Graves disease and high levels of thyroid-stimulating antibodies. To confirm the diagnosis, doctors do tests to determine levels of thyroid hormones in the blood (thyroid function tests Thyroid function tests The thyroid is a small gland, measuring about 2 inches (5 centimeters) across, that lies just under the skin below the Adam’s apple in the neck. The two halves (lobes) of the gland are connected... read more ).
In older children and adolescents, doctors do thyroid function tests. Doctors also do ultrasonography Ultrasonography Ultrasonography uses high-frequency sound (ultrasound) waves to produce images of internal organs and other tissues. A device called a transducer converts electrical current into sound waves... read more on older children who have Graves disease if the thyroid gland feels asymmetric or they feel a growth (nodule) on the thyroid gland. If a nodule is found during ultrasonography, doctors remove a piece of it using a needle (called fine-needle aspiration biopsy) to determine whether the child has thyroid cancer. Doctors may also do an imaging test called radionuclide scanning Radionuclide Scanning In radionuclide scanning, radionuclides are used to produce images. A radionuclide is a radioactive form of an element, which means it is an unstable atom that becomes more stable by releasing... read more to see whether the nodule is the source of the excess thyroid hormone.
Infants who developed hyperthyroidism as a fetus may be severely affected if hyperthyroidism is not detected until birth. The space between their skull bones may close too soon (called craniosynostosis Craniosynostosis Craniosynostosis is a birth defect in which one or more of the skull's sutures close too early. (See also Introduction to Birth Defects of the Face, Bones, Joints, and Muscles.) The sutures... read more ) and they may have intellectual disability, growth failure, and short stature. About 10 to 15% of infants may die.
Infants who have neonatal Graves disease almost always recover within 6 months. If the mother did not take drugs that decrease the thyroid gland's production of thyroid hormones (antithyroid drugs) while pregnant, the infant will have hyperthyroidism at birth. If the mother did take the drugs while pregnant, the infant may not show symptoms of hyperthyroidism for about 3 to 7 days after birth. (See also treatment of Graves disease during pregnancy Graves disease Thyroid disorders may be present before women become pregnant, or they may develop during pregnancy. Being pregnant does not change the symptoms of thyroid disorders. How the fetus is affected... read more .)
Older children who have Graves disease may respond to antithyroid drugs or may need additional treatments to permanently treat the disorder if antithyroid drugs are not effective or if symptoms return.
Sometimes iodine or hydrocortisone
Children are given antithyroid drugs (such as methimazole), which decrease the thyroid gland's production of thyroid hormones, and beta-blockers, which are drugs that slow the heart rate. Beta-blockers are used only if the heart rate is too fast or blood pressure is too high. Treatment with beta-blockers is stopped after the antithyroid drugs have taken effect. For severe cases, such as thyroid storm, children may also be given drops of iodine by mouth or hydrocortisone by vein, but this complication is rare.
Infants who have neonatal hyperthyroidism almost always recover by 6 months and no longer need antithyroid drugs. Symptoms in older children treated with antithyroid drugs may eventually disappear (called remission), but symptoms may return (called relapse) in some children and they may need further treatment.
Sometimes children with Graves disease need additional treatments to permanently treat the disorder. Permanent treatment (definitive therapy) may be needed if the antithyroid drugs do not work (or the child does not take them) or if the drugs are causing serious side effects. In definitive therapy, the gland is destroyed with radioactive iodine or removed with surgery. However, radioactive iodine is usually not given to children who are under age 10 and is often not effective in people who have larger thyroid glands. Therefore, surgery may be done instead for children and adolescents who have these factors.
Nodules are removed surgically.
Acute thyroiditis is treated with antibiotics. Subacute thyroiditis is not treated with antibiotics, but nonsteroidal anti-inflammatory drugs (NSAIDs) are given for pain. Children are not given antithyroid drugs, but beta-blockers may be given.