Hyperthyroidism in the newborn is usually caused by Graves disease in the mother.
Symptoms include irritability, rapid heart rate, bulging eyes, and delayed weight gain.
The diagnosis is based on thyroid function tests.
This disorder can be fatal if left untreated.
Treatment typically includes antithyroid drugs and beta-blockers.
(See also Overview of General Problems in Newborns Overview of General Problems in Newborns Problems in newborns may develop Before birth while the fetus is growing During labor and delivery After birth About 10% of newborns need special care after birth due to prematurity, problems... read more , 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, and Hyperthyroidism in Infants and Children Hyperthyroidism in Infants and Children 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... read more .)
The thyroid gland Overview of the Thyroid Gland 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 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.
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 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 , 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 Premature Newborn A premature newborn is a baby delivered before 37 weeks of gestation. Depending on when they are born, premature newborns have underdeveloped organs, which may not be ready to function outside... read more . Because newborns are no longer exposed to the mother's antibodies after birth, Graves disease in the newborn is usually temporary but may come back.
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 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 Vomiting in Infants and Children Vomiting is the uncomfortable, involuntary, forceful throwing up of food. In infants, vomiting must be distinguished from spitting up. Infants often spit up small amounts while being fed or... read more , and diarrhea Diarrhea in Children Diarrhea is a very common problem in children (see also Diarrhea in adults). Diarrhea is frequent, loose, or watery bowel movements (BMs) that differ from a child’s normal pattern. Sometimes... read more . The newborn, like the mother, may have bulging eyes Eyes, Bulging Bulging or protruding of one or both eyes is called proptosis or exophthalmos. Exophthalmos is usually used when describing bulging eyes caused by Graves disease, a disorder causing overactivity... read more (exophthalmos). If the newborn has an enlarged thyroid gland (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 ), 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 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 ), intellectual disability 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 , growth failure, short stature Growth Hormone Deficiency in Children Growth hormone deficiency occurs when the pituitary gland does not produce enough growth hormone. Growth hormone deficiency is the most common pituitary hormone deficiency and is accompanied... read more , and hyperactivity later in childhood.
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.
Doctors suspect hyperthyroidism if the newborn's mother has Graves disease and if the newborn has typical symptoms.
Doctors then confirm the diagnosis by doing blood tests called 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 to detect elevated levels of thyroid hormone and thyroid-stimulating antibodies from the mother in the newborn’s blood.
After hyperthyroidism of the newborn is diagnosed, doctors may do imaging tests to evaluate the size and location of the thyroid gland.
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 .)
Newborns with hyperthyroidism are treated with antithyroid drugs that slow the production of thyroid hormone by the thyroid gland (such as methimazole). They also are given beta-blockers, which slow the heart rate (such as propranolol). Infants may also be given drops of iodine by mouth or hydrocortisone by vein if other therapies have not helped. These drugs are stopped as soon as the antibodies that cross the placenta from the mother have disappeared from the infant’s bloodstream.