Hyperthyroidism is increased production of thyroid hormone.
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.
Treatment typically includes antithyroid drugs and beta-blockers.
(See also Hyperthyroidism in adults.)
The thyroid gland is an endocrine gland located in the neck. Endocrine glands secrete hormones into the bloodstream. Hormones 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 newborn or during childhood or adolescence.
Newborns
Hyperthyroidism, or Graves disease in the newborn (neonatal Graves disease), is rare in newborns but is potentially fatal if not recognized and treated by a medical doctor who specializes in disorders of the endocrine glands in children (pediatric endocrinologist). This condition usually occurs if the mother has Graves disease during pregnancy or has been treated for it before pregnancy. In Graves disease, the mother’s body produces antibodies that stimulate her thyroid gland to produce increased amounts of thyroid hormone. These antibodies cross the placenta and also cause the fetus's thyroid gland to produce too much thyroid hormone, which can result in death of the fetus or premature birth. Because newborns are no longer exposed to the mother's antibodies after birth, Graves disease in the newborn 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. The rate of Graves disease increases during puberty, and 80% of cases happen after 11 years of age. Many children with Graves disease have a family history of autoimmune thyroid disease or other autoimmune disorders. Children with Down syndrome are at increased risk of Graves disease.
Less common causes of hyperthyroidism in children and adolescents include growths (nodules) on the thyroid gland, inflammation of the thyroid gland (Hashimoto thyroiditis, in which hyperthyroidism is temporary and children eventually develop hypothyroidism), and some drugs. Occasionally, temporary hyperthyroidism can be caused by infections, including bacterial (acute thyroiditis) and viral (subacute thyroiditis) infections.
Symptoms
Symptoms of hyperthyroidism differ depending on the age of the child.
Fetuses
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). If the disorder is present and untreated for a long period before birth, about 10 to 15% of newborns die and others have impaired intellectual development, poor growth, and short stature.
Newborns
An affected newborn has increased bodily functions, such as a rapid heart rate and breathing, irritability, and excessive appetite with poor weight gain. Other symptoms include failure to thrive, vomiting, and diarrhea. The newborn, like the mother, may have bulging eyes (exophthalmos). If the newborn has an enlarged thyroid gland (congenital goiter), the gland may press against the windpipe and interfere with breathing at birth. A very rapid heart rate can lead to heart failure.
Untreated hyperthyroidism may result in early closing of the bones of the skull (craniosynostosis), intellectual disability, growth failure, short stature, and hyperactivity later in childhood.
Children and adolescents
Symptoms of hyperthyroidism reflect the speeding up of bodily functions:
Sleep difficulties
Hyperactivity
Sweating
Fatigue
Weight loss
Increased heart rate and blood pressure
Frequent bowel movements
Tremors (shakiness)
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 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. Thyroid storm can lead to coma and death.
Diagnosis
Thyroid function tests
Sometimes imaging tests
In newborns, doctors suspect hyperthyroidism if the mother has active Graves disease or a history of Graves disease and high levels of thyroid-stimulating antibodies. The results of the routine screening blood test done in the hospital after birth to evaluate thyroid function, which is done mainly to look for hypothyroidism, may reveal hyperthyroidism in the newborn. To confirm the diagnosis, doctors do tests to determine levels of thyroid hormones in the blood (thyroid function tests). After hyperthyroidism of the newborn is diagnosed, doctors may do imaging tests to evaluate the size and location of the thyroid gland.
In older children and adolescents, doctors do thyroid function tests
Doctors also do ultrasonography on older children who have Graves disease if the thyroid gland feels asymmetric or they feel a growth (nodule) on the thyroid gland. Computed tomography (CT) or ultrasonography may also be done if doctors suspect a pocket of pus (abscess) or birth defect. 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 to evaluate a nodule.
Prognosis
Newborns 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), and they may have intellectual disability, growth failure, and short stature. About 10 to 15% of newborns may die.
Newborns 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 newborn will have hyperthyroidism at birth. If the mother did take the drugs while pregnant, the newborn may not show symptoms of hyperthyroidism for about 3 to 7 days after birth. (See also treatment of Graves disease during pregnancy.)
Older children who have Graves disease may respond to antithyroid drugs. They may need additional treatments to permanently treat the disorder if antithyroid drugs are not effective or if symptoms return.
Treatment
Antithyroid drugs
Beta-blockers
Sometimes surgery
hypothyroidism, which can affect growth and development.
Newborns 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 older children (11 years of age and older) 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.
