The thyroid gland secretes thyroid hormones; thyroid hormone controls the speed of body’s metabolism, including: heart rate and body temperature. The hypothyroidism occurs when the thyroid gland is underactive and doesn’t produce enough thyroid hormone to meet the body’s needs. Healthy thyroid function is critical for infants and children, whose developing brains and bodies rely on adequate levels of thyroid hormone. When hypothyroidism in infants isn’t treated, even mild cases can lead to severe physical and mental retardation. There are two types of hypothyroidism in infants and children: Congenital hypothyroidism, which is present at birth, and acquired hypothyroidism, which develops after birth, usually during late childhood or adolescence.
Hypothyroidism in newborns can occur for a variety of reasons. The most common cause of hypothyroidism in the newborn are:
Because early treatment can prevent intellectual disability, all newborns receive a routine screening blood test in the hospital after birth to evaluate thyroid function. In affected newborns, the blood test shows an elevated level of thyroid-stimulating hormone and usually a lower level of thyroid hormone. If the result of the screening test is positive, thyroid function tests, are done. After hypothyroidism of the newborn is diagnosed, doctors do scanning tests to evaluate the size and location of the thyroid gland. These tests include radionuclide scanning or ultrasonography.
If the diagnosis is confirmed through further thyroid tests, newborns must be treated as quickly as possible. Treatment of hypothyroidism is directed by a doctor who specializes in treating children with problems of the endocrine system (called a pediatric endocrinologist). The treatment is usually with synthetic thyroid hormone, which should be given as a crushed pill mixed with a small amount of breast milk. It should not be given with iron or calcium supplements, which can reduce absorption of replacement hormone.
Children who are born with a severely underactive thyroid gland can develop intellectual disability if the condition isn’t treated quickly. Even with treatment, some children with congenital hypothyroidism may be slower to learn than other kids their age. Other complications of congenital hypothyroidism include: