Résumé
BACKGROUND: False positive rate of 17-OHP screening test was higher more than other screening tests due to use same cutoff value both term and preterm infants in Korea. The purpose of this study is to set cutoff value of 17-OHP on the basis of birth weight in neonatal screening for congenital adrenal hyperplasia. METHODS: 17-OHP was measured in filter paper blood spots obtained by heel puncture between 3 and 7 days after birth. 17-OHP values were analyzed with respect to birth weight in order to decide the appropriate cutoff values in a neonatal screening for congenital adrenal hyperplasia. RESULTS: The mean concentrations of 17-OHP according to birth weight groups were as follows : 12.6, 7.0, 5.1, 3.7, 3.0, 2.5 ng/mL for birth weight of 1.50 or less, 1.50-1.99, 2.00-2.49, 2.50-2.99, 3.00-3.49, 3.50 kg or more, respectively. The cutoff values for determining the 17-OHP for recall were decided as follows : 55, 35, 18, 11, 8, 8 ng/mL for birth weight of 1.50 or less, 1.50-1.99, 2.00-2.49, 2.50-2.99, 3.00-3.49, 3.50 kg or more, respectively. Application of the new cutoff values according to birth weight dropped the total recall rate from 3.3% to 1.0%. CONCLUSIONS: The cutoff values of 17-OHP on the basis of birth weight should be used in the neonatal screening for congenital adrenal hyperplasia. We believe that the recall rate due to false positive can be reduced using this method in low birth weight infants.