(For adults, also see Goiter.)
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. Thyroid hormone regulates the rate at which the body functions (metabolic rate).
Congenital goiters may be caused by the following:
The thyroid gland secretes thyroid hormone. Any thyroid gland disorder that decreases production of thyroid hormone causes the pituitary gland to secrete more thyroid-stimulating hormone (TSH). If a disorder prevents the thyroid gland from responding normally by increasing hormone output, the increased stimulation by TSH causes the thyroid gland to enlarge. There are many genetic abnormalities that decrease the thyroid gland's ability to produce thyroid hormone and cause congenital goiter.
Women who have certain thyroid disorders such as Graves disease sometimes produce antibodies that cross the placenta during pregnancy. These antibodies interact with the receptor for TSH and can cause the fetus to produce too much thyroid hormone (hyperthyroidism) or too little thyroid hormone (hypothyroidism). But in both cases, a goiter may result. In affected infants, the goiter typically resolves spontaneously within 3 to 6 months.
Drugs such as amiodarone, propylthiouracil, and methimazole taken by the mother can cross the placenta and may rarely cause congenital goiter.
The most common symptom of congenital goiter is firm enlargement of the thyroid. There is no tenderness. The entire gland may be enlarged or only portions of it. It may be noticeable at birth or detected later. If the enlargement continues, infants may have difficulty breathing and swallowing. Many infants with goiters have a normally functioning thyroid gland. However, some infants develop hypothyroidism or hyperthyroidism.