(See also Simple Nontoxic Goiter in adults and Overview of Thyroid Function.)
Etiology
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.
Dyshormonogenesis
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
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
Symptoms and Signs
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
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.
