Screening of congenital hypothyroidism in newborns in Bohemia and Moravia.

Regular examinations of thyroid function in newborn infants were started in the district of Praha 10 in 1975. Later the incidence of congenital hypothyroidism in Czechoslovakia was assessed in a pilot study including several centers in 1981. As a screening method we used the estimation of total thyroxine (T4) in a dried spot of blood obtained from a heel prick on the fifth day after birth. A total of 45,535 newborns was screened by such method and the incidence was 1:5059 of live born infants. Since 1985 the screening of congenital hypothyroidism has been extended to cover the whole territory of Czechoslovakia. Three screening centers (in Praha, Brno and Banská Bystrica) are responsible for carrying out this screening program. The first screening method employed was the determination of total thyroxine in a dried spot of blood on filter paper as mentioned above. By the end of December 1987, 313,618 samples from newborns have been assayed in Bohemia and Moravia. The incidence of congenital hypothyroidism was found to be 1:5700 of live newborn infants. The treatment of detected cases was started before the end of the first month after birth which ensured normal development of children thus afflicted. When T4 was the first method employed, a relatively high incidence of altered TBG (thyroxine binding globulin) production (1:6400) was encountered, especially in boys.