Screening for neonatal hypothyroidism in Israel during a 4-year period.

The neonatal hypothyroidism (NH) screening program in Israel was initiated in May 1978, and by the end of April 1984, 538,565 infants had been screened. One hundred sixty-six newborns were found to have NH; 7 of these exhibited only transient hypothyroidism. During the screening period the average age for initiation of treatment decreased from 6 to 4.8 weeks. A thyroid scan was performed on 51 of the neonates with NH; 41% had agenesis of the thyroid, 24% ectopic thyroid tissue, 29% dyshormonogenesis, and 6% secondary or tertiary hypothyroidism. This high incidence of dyshormonogenesis in Israel is probably due to a high rate of consanguinity among the Arab population and also within some of the Jewish ethnic groups. No blood sample was received from four infants with NH, and one infant with NH was not notified. This study indicates that a neonatal screening program can effectively detect infants with NH, resulting in earlier treatment.