Pitfall of newborn screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency

We report on a newborn with a severe salt-wasting crisis due to congenital adrenal hyperplasia (CAH) with 21-hydroxylase deficiency, in spite of prenatal diagnosis of CAH and awareness of this diagnosis by the parents and the gynecologic and pediatric practitioners. Due to the diagnosis of CAH in the older sister, prenatal treatment with dexamethasone (Dexa) was initiated. Prenatal diagnosis showed an affected male fetus and the prenatal treatment was stopped. The parents and the involved physicians were informed about the diagnosis, treatment, follow-up, and possible complications. Amniotic infection led to preterm delivery in another hospital. Due to perinatal asphyxia, the male newborn received Dexa during mechanical ventilation. Neonatal CAH screening was unsuspicious. An acute salt-wasting crisis with metabolic acidosis at the age of 3 weeks finally led to the correct diagnosis. This experience emphasizes the need to obtain a careful medical history. Furthermore, this case illustrates that neonatal screening for CAH is falsely negative in the event of neonatal Dexa treatment.