Screening for congenital hypothyroidism. Results in the newborn population of New England

Abstract

During the 1st yr of operation, the New England Regional Hypothyroidism Screening Program determined the concentration of thyroxine (T4) levels in dried blood on filter paper from 129,028 infants born in Connecticut, Maine, Massachusetts, New Hampshire and Rhode Island [USA]. Specimens from approximately 3800 neonates had levels of T4 below the lower limit of normal (< 6.0 .mu.g/dl) and were assayed for thyroid-stimulating hormone (TSH) content. Levels of TSH were elevated (> 20 .mu.U/ml) in 31 infants, 23 of whom eventually proved to have unequivocal hypothyroidism. Based on these figures and including 2 hypothyroid infants who were not tested, the incidence of congenital hypothyroidism in the New England region is approximately 1:5200 births. The estimation of T4 values supplemented by measurement of TSH values on specimens with low T4 values proved to be a satisfactory approach to large-scale screening for congenital hypothyroidism.