Children may have goiters that are diffuse or nodular, and the goiters may be associated with normal, decreased, or increased thyroid hormone production. The causes of goiter in children and adults are similar, but their relative frequency varies substantially. In the United States, for example, most children with a goiter have chronic autoimmune thyroiditis, whereas among adults, nontoxic nodular goiters predominate.
Goiter may be present at birth or detected at any age thereafter. The goiter may be caused by increased thyrotropin (TSH) secretion (acting as a thyroid growth factor) resulting from hypothyroidism; antibodies that activate TSH receptors (Graves' disease) with increased thyroid hormone secretion; or TSH-independent processes, such as inflammation associated with autoimmune thyroiditis, benign and malignant tumors, and infiltrative disease.
Once a goiter is detected, the appropriate diagnostic evaluation is aimed at identifying the underlying cause and assessing thyroid function. Both of these factors will determine management. This topic review will consider congenital and acquired goiters, independent of their function, in infants and children.
Thyroid nodules and cancers, and the causes of hypothyroidism and hyperthyroidism in children are discussed separately. (See "Thyroid nodules and cancer in children" and "Clinical manifestations and diagnosis of hyperthyroidism in children and adolescents" and "Acquired hypothyroidism in childhood and adolescence".)
THYROID SIZE IN INFANTS AND CHILDREN
The mean (±SD) thyroid volume, measured by ultrasonography, in 68 term neonates in Chicago was 0.9 ± 0.2 mL . In an extensive study of 7- to 14-year-old children from an iodine-sufficient area of Italy, the mean thyroid volume increased with age from 3.1 to 6.3 mL (table 1) . Thyroid size correlates with body surface area; among children 6 to 14 years of age, the upper 95th percentile was 6.2 mL per m2 in one series . In a report of 6- to 12-year old children from Japan, where intake of iodine is relatively high (median urinary iodine 281.6 mcg/L), thyroid volumes were smaller, increasing from 1.5 mL to 3.8 mL over this age period . Clinically, we use the "rule of thumb" to evaluate thyroid size in older children: each lobe of the normal thyroid gland is approximately the size of the terminal phalanx of the child's thumb.