Congenital goiter is a diffuse or nodular enlargement of the thyroid gland present at birth. Thyroid hormone secretion may be decreased, increased, or normal. Diagnosis is by confirming thyroid size with ultrasonography. Treatment is thyroid hormone replacement when hypothyroidism is the cause. Surgery is indicated when breathing or swallowing is impaired.
Etiology of Congenital Goiter
Congenital goiter may be caused by dyshormonogenesis (abnormal thyroid hormone production), transplacental passage of maternal antibodies, or transplacental passage of goitrogens. Some causes of congenital goiter are hereditary.
Genetic defects in thyroid hormone production result in increased levels of thyroid-stimulating hormone (TSH), which in turn can cause congenital goiter. Goiter is present in about 15% of cases of congenital hypothyroidism. There are a number of gene abnormalities that cause dyshormonogenesis; they commonly have an autosomal recessive form of inheritance, and many are single-gene defects.
Dyshormonogenesis can result from a defect in any of the steps in thyroid hormone biosynthesis, including
- Failure to concentrate iodide
- Defective organification of iodide due to an abnormality in the thyroid peroxidase enzyme or in the hydrogen peroxide–generating system
- Defective thyroglobulin synthesis or transport
- Abnormal iodotyrosine deiodinase activity
Children with Pendred syndrome have mild hypothyroidism or euthyroidism, goiter, and sensorineural hearing loss due to a genetic abnormality of a protein (pendrin) involved in iodine transport and cochlear function. Although Pendred syndrome is caused by a genetic defect, it rarely manifests in the newborn period.
Transplacental passage of maternal antibodies
Women with an autoimmune thyroid disorder produce antibodies that may cross the placenta during the 3rd trimester. Depending on the disorder, the antibodies either block thyroid-stimulating hormone receptors, causing hypothyroidism, or stimulate them, causing hyperthyroidism. Typically, in affected infants, the changes in hormone secretion and the associated goiter resolve spontaneously within 3 to 6 months.
Transplacental passage of goitrogens
Goitrogens, such as amiodarone or antithyroid drugs (eg, propylthiouracil, methimazole), taken by the mother can cross the placenta, sometimes causing hypothyroidism and rarely causing goiter.
Symptoms and Signs of Congenital Goiter
The most common manifestation of congenital goiter is firm, nontender enlargement of the thyroid. Enlargement is most often diffuse but can be nodular. It may be noticeable at birth or detected later. In some patients, enlargement is not directly observable, but continued growth can cause deviation or compression of the trachea, compromising breathing and swallowing. Many children with goiters are euthyroid, but some present with hypothyroidism or hyperthyroidism.
Diagnosis of Congenital Goiter
If the diagnosis of congenital goiter is suspected, thyroid size is typically assessed by ultrasonography. Free thyroxine (T4) and thyroid-stimulating hormone levels are measured.
Treatment of Congenital Goiter
- Surgical treatment of enlargement causing symptoms related to compression
- Sometimes thyroid hormone
Hypothyroidism is treated with thyroid hormone.
Goiters that compromise breathing and swallowing can be treated surgically.
Drugs Mentioned In This Article
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|propylthiouracil||No US brand name|