[Mental development in congenital hypothyroidism. Results of a survey in 14 European countries].

Although newborn screening for congenital hypothyroidism was introduced into Europe as late as 1975, its high acceptance rate has quickly led to its wide use in most European countries. One would expect early diagnosis with early onset of treatment to result in normalization of previously impaired mental development. One may conclude from results obtained in 790 children up to the age of seven years that normal mental development is assured if levothyroxine is administered within the first four weeks of life. This also applies to children with athyroidism: their mental development is not different from that of children with an ectopic thyroid.