The thyroxine screening index in congenital hypothyroidism screening

A modification of the RIA total thyroxine assay from a dry drop of blood has been applied in 5-day-old neonates for the screening of congenital hypothyroidism. For first classification, the thyroxine screening index was used in 13 500 newborns; it proved to be simple, rapid and economically acceptable. In borderline cases, more detailed examinations were carried out, viz. estimation by RIA of thyroid stimulating hormone, thyroxine and thyroxine-binding globulin from venous blood. The incidence of permanent and transient impairment of thyroid function is shown in a special graph.