Elevated levels of certain substances associated with the thyroid gland--some of them produced by the thyroid itself and others produced elsewhere in the body but targeting the thyroid--can be markers for a number of diseases or clinical abnormalities. While thyroid disorders are seen less often in children than in adults, congenital and acquired thyroid conditions in children are not rare; for example, about 1 in every 3,500 to 5,000 babies is born with hypothyroidism.
Features
Childhood thyroid disorders manifest clinically in many of the same ways they do in adults. Blood testing is critical for diagnosis these disorders and usually reveals high or low levels of one or more of the following, depending on the specific malady: thyroid-releasing hormone or TRH, secreted by the hypothalamus when T4 is low; thyroid-stimulating hormone or TSH, secreted by the pituitary in response to TRH; T3 and T4, secreted by the thyroid gland in response to stimulation by TSH, with T4--also called thyroxine-- being the more metabolically active substance and the one people generally mean by "thyroid hormone."
Types
Hyperthyroidism refers to an overactive thyroid and in infants results from an excess of maternal T4, as in Graves' disease. Hyperthyroidism can be primary, or resulting from a thyroid gland secreting excess T4 without provocation, or secondary, or caused by a pituitary tumor or other source of excess TSH secretion. Hypothyroidism refers to an underactive thyroid, and again may be primary--resulting from a thyroid unresponsive to TSH--or secondary--owing to a failure of the pituitary to secrete TSH.
Effects
Hyperthyroidism in infants has a panoply of symptoms, including irritability, feeding problems, hypertension, tachycardia, exophthalmos or "bug eyes," goiter, failure to thrive, vomiting and diarrhea; if uncorrected it may lead to impaired brain development, short stature, and hyperactivity later in childhood. In children and adolescents it is characterized primarily by goiter, thyrotoxicosis and ophthalmopathy. Hypothyroidism in infants is marked by poor feeding and growth failure, while in older children and adolescents growth failure, delayed puberty or both are common findings.
Significance
While hyperthyroid infants usually recover within six months unresolved cases may have dire consequences; in some setting 10 to 15 percent die, and others are permanently left with the physical effects of insufficient physical and mental growth and development. persistent hypothyroidism also slows neurological development, and may be accompanied by poor muscle tone, elevated bilirubin, respiratory distress, and poor feeding and hoarse crying; intellectual disability and short stature are rare but serious complications. In older children and adolescents, manifestations mimic those of hypothyroid adults--weight gain; constipation, dry hair, and various skin problems.
Prevention/Solution
The treatment of hyperthyroidism and hyperthyroidism in children depends, of course, on the specific cause; each disorder can result from a number of sources. Antithyroid drugs, radioactive iodine and occasionally surgery are the treatments of choice for hyperthyroidism in both infants and older children while congenital hypothyroidism--just as in adults--entails lifelong thyroid hormone replacement.
