An Analysis of Two-Year Experience in Neonatal Screening

Kim, In Suk; Lee, Soo Youn; Kim, Jong Won

Abstract

BACKGROUND
This study was undertaken to evaluate whether the currently used cut-offs are appropriate and whether there is a significant relationship between false positive results and post-natal well being in neonatal screening. METHODS: During the period of January 2001 through December 2002 at Samsung Medical Cen-ter, neonatal screening tests for TSH, free thyroxine (FT4), phenylketonuria (PKU), galactosemia and 17-hydroxyprogesterone (17-OHP) were performed in newborns using commercial ELISA kits. We reviewed the recall rates at currently used cut-offs and analyzed the relationship between false positive results and postnatal well-being. RESULTS: We obtained false positive results of 2.42%, 0.86%, 1.5%, 0.95% and 0.97% for TSH, FT4, PKU, galactosemia, and 17-OHP, respectively. Twelve babies out of 5, 918 was diagnosed with hypothyroidism. The false positive results of 17-OHP and FT4 were mostly seen in premature babies. Simultaneous false positive results of 17-OHP and other neonatal screen such as FT4 or galactosemia showed poor prognostic outcome in premature babies (odds ratio 6.08, P=0.0006). CONCLUSIONS: In galactosemia, PKU, and 17-OHP, it would be reasonable to modify the cut-offs to 99.7 percentile after measuring those substances from enough number of healthy neonates. The babies who have been treated with L-thyroxine by the current cut-offs of TSH or FT4 were relatively large in number, thus, prospective follow-up of evaluation of the cut-offs of TSH or FT4 is necessary. Also, a simultaneous positivity of 17-OHP and FT4 or galactosemia could be considered as a poor prognostic factor in postnatal well-being.