DESCRIPTION

A goiter is an enlarged thyroid gland (also known as thyromegaly). A simple or colloid goiter is not associated with thyroid dysfunction, autoimmune thyroid disease, or neoplastic process. Thyroid nodules are present in some goiters.

EPIDEMIOLOGY

• The incidence of goiter in school-age children ranges from 1.9% to 6.8%.
• The prevalence of goiter in the United States is 3–7%, although prevalence is much higher in regions of iodine deficiency (15.8% globally).
• Prevalence in childhood peaks during adolescence with females more affected than males.
• Thyroid cancer is a rare cause of pediatric goiter.

ETIOLOGY

• The most common cause of pediatric goiter in the United States is chronic lymphocytic thyroiditis (Hashimoto thyroiditis).
• Genetic etiologies as listed previously

RISK FACTORS

• Family history
• Female sex
• Autoimmune disease such as type 1 diabetes
• Tobacco smoke
• Radiation
• Iodine deficiency or excess
• Certain drugs (e.g., lithium, tyrosine kinase inhibitors, some anticonvulsants)
• Certain chromosomal differences (Down syndrome, Turner syndrome)

GENERAL PREVENTION

Iodine administration reduces endemic goiter incidence.

PATHOPHYSIOLOGY

• In autoimmune thyroid disease, thyromegaly results from thyrotropin receptor stimulation, either by increased TSH in the setting of hypothyroidism or TSH-receptor stimulating antibodies.
• Thyroid enlargement can also develop due to inflammation, as seen in thyroiditis, or infiltration.
• The pathogenesis of euthyroid simple goiter remains unclear.

COMMONLY ASSOCIATED CONDITIONS

• Autoimmune thyroid disease is associated with certain genetic disorders and other autoimmune diseases.
  • Down syndrome and Turner syndrome
  • Type 1 diabetes and celiac disease
    • Autoimmune polyglandular syndrome type 2 (APS-2): Addison disease plus Hashimoto thyroiditis and/or type 1 diabetes
• Pendred syndrome: congenital sensorineural deafness and goiter due to mutation in pendrin, which transports iodide into the thyroid follicular lumen