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

Congenital goiters may be caused by dyshormonogenesis (abnormal thyroid hormone production), transplacental passage of maternal antibodies, or transplacental passage of goitrogens. Some causes 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. There are 4 main types of dyshormonogenesis.

• Type 1 is caused by a defect in iodide transport secondary to altered synthesis of a cell surface protein necessary for transport.
• Type 2 is caused by one of several defects in thyroid iodination mechanisms. The enzyme peroxidase, necessary for iodine organification, may be absent (resulting in goitrous cretinism) or dysfunctional. Another defect may impair hydrogen peroxide generation. Children with Pendred's syndrome have mild hypothyroidism or euthyroidism, goiter, and sensorineural hearing loss due to an abnormal transport protein (pendrin) involved in iodine transport and cochlear function.
• Type 3 is caused by complete or partial deiodination defects of monoiodotyrosine and diiodotyrosine in thyroglobulin.
• Type 4 is caused by one of several defects in thyroglobulin synthesis, usually via X-linked inheritance and thus commonly occurs in boys. This condition does not cause clinical hypothyroidism. It is, however, characterized by a very low level of total serum thyroxine (T₄) but normal levels of free T₄ and TSH.

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 TSH 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 mo.

Transplacental passage of goitrogens

Goitrogens such as amiodarone or antithyroid drugs (eg, propylthiouracil, methimazole) can cross the placenta, sometimes causing hypothyroidism and rarely causing goiter.

Symptoms and Signs

The most common manifestation 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 is suspected, thyroid size is typically assessed by ultrasonography. T₄ and TSH are measured.

Treatment

Hypothyroidism is treated with thyroid hormone. Goiters that compromise breathing and swallowing can be treated surgically.

Last full review/revision May 2009 by Nicholas Jospe, MD