The adjustment of 17-hydroxyprogesterone cut-off values for congenital adrenal hyperplasia neonatal screening by GSP according to gestational age and age at sampling.

Background Congenital adrenal hyperplasia (CAH) screening is facing great challenges because of a high false-positive rate and a low positive predictive value (PPV). We established and optimized 17-hydroxyprogesterone (17-OHP) cut-off values for CAH neonatal screening using a genetic screening processor (GSP) according to gestational age (GA), birth weight (BW) and age at sampling. Methods The 17-OHP concentrations in dried blood spots were measured by time-resolved immunofluorescence and were grouped in terms of GA, BW and age at sampling for 48,592 newborns. The 99.5th percentile was used to set an initial cut-off value as a reference. Results Significant differences in 17-OHP concentrations were observed among newborns with different GAs and BWs. A significant difference was observed among different sampling age groups. Finally, we defined new multitier cut-off concentrations based on GA and age at sampling. Application of the new cut-off values resulted in a 30% reduction of the positive rate and a 40% increase of the PPV. Conclusions GA, BW and sampling age time influenced the concentrations of 17-OHP. The efficiency of congenital adrenal hyperplasia screening can be substantially improved by adjusting the multitier cut-off value according to GA and age at sampling.