Neonatal screening for congenital adrenal hyperplasia: 17-hydroxyprogesterone cut-off values based on birth weight

Introduction: Congenital adrenal hyperplasia (CAH) is an adrenal disorder, most commonly caused by 21- hydroxylase enzyme deficiency. Newborn screening for CAH is done by the measurement of 17-hydroxyprogesterone (17-OHP). Aim: To establish the reference limits of 17-OHP in newborns. Materials and Methods: The study was conducted at Sri Ramachandra Medical College and Research Institute (SRMC& RI), Chennai. The clinical data of 360 neonates delivered over a period of two years from January 2015 to December 2016 were retrospectively analyzed. The newborns were grouped according to birth-weight: G1: < 1>2250 g. Based on birth weights 17-OHP cut-off values were determined for each group by rank number. Results: The reference limits for the three group, < 1>2250 g are 2.23 - 59.3, 1.9 - 29.7 and 1.9 - 15.1 nmol/L respectively. The upper reference limits of all the groups are less than the values showed in the kit literature. Conclusion: CAH can be diagnosed by measuring 17-OHP at birth as a part of neonatal screening. Population specific and birth weight specific cut off values of 17-OHP will reduce the false positives.