Re-evaluation of TSH screening test in neonates

ABSTRACT

Five years ago, we made the cut-off value of Tsh by dry filter paper method as 15 microU/ml to sereening congenital hypothyroidism. Since then, 1,210 term neonates, who had no perinatal problems, were born in SNUCH between Aug. 1987 and Apr. 1992, had been performed this neonatal Tsh screening test with this cut-off point. Neonates had been recalled for measurement of serum T4/TSH to rule out congenital hypoothyroidism if their TSH value by screening tests reveal more than 15 microU/ml. Because there had been high false-positive rate during 5 years, we felt thiscut-off value of TSH should be set higher than 15 microU/ml with same method. Therefore, we analyzedthis TSH values to set a new cut-off point to recall the neonates. The results ars asbelow 1) TSH value by dry filter paper method was 8.48+/-4.41 U/ml(mean+/-S.D.) 2) Assuming 15 microU/ml as a cut-off point for recall the neonates, the false positive fate is 8.01% 3) Tomake the false positive rates as 0.3%, it is reasonable to set the cut-off point at 22 microU/ml, whichis +/-3S.D.(99.7 percentile) of measured TSH level by dry filter paper method.