Just to orient you a bit, congenital hypothyroidism is a disorder caused most commonly either by failure of thyroid gland development or failure of thyroid hormone synthesis. This first slide demonstrates the devastating impact of this disorder on a small infant whose congenital hypothyroidism was undiagnosed and untreated. Because at birth, affected babies have no symptoms and because for the best outcome, treatment must be started as early as possible, screening programs for the detection of congenital hypothyroidism have been developed in the United States and throughout the world.
We now know that the incidence of congenital hypothyroidism is 1 in 3,000 babies and as such, this disorder is one of the most common treatable causes of mental retardation. In fact, congenital hypothyroidism is now known to be three to four times more common than PKU for which newborn screening programs were originally developed.
The second slide demonstrates some data prior to the advent of newborn thyroid screening, demonstrating the significant decrease in IQ of babies with congenital