Newborn screening for congenital adrenal hyperplasia in the Netherlands.

OBJECTIVE: To evaluate whether congenital adrenal hyperplasia (CAH) patients can be detected by newborn screening before the occurrence of life-threatening salt wasting and whether the prevalence, specificity, and sensitivity are adequate enough for a routine screening procedure.
DESIGN: From 1998, a 2-year regional pilot screening for CAH was performed. In 1998, cutoff levels for 17OHP were primarily based on birth weight, and in 1999 on gestational age. In addition, nationwide, all newly diagnosed patients with CAH were reported to the Dutch Pediatric Surveillance Unit to compare screened CAH patients with CAH patients in the area without screening.
RESULTS: In 2 years, 176 684 newborns were screened and 15 CAH patients (7 males/8 females) were detected. Therapy was started at the median age of 7 days. In the area without screening, 223 307 infants were born and 19 CAH patients (10 males/9 females) were reported to the Dutch Pediatric Surveillance Unit. Therapy was started at the median age of 14 days. The mean (standard deviation) serum sodium concentration was 134.5 (3.4) mmol/L in the area of screening versus 124.5 (10.8) mmol/L in the area without screening. The overall prevalence was 1:11 764. In 1998 and 1999, the specificity was 99.76% and 99.97%, respectively. The positive predictive value was 4.5% and 16%, respectively. To date, no false-negative cases have been detected.
CONCLUSION: Severe salt wasting can be prevented by neonatal screening. The prevalence, specificity, and sensitivity allowed addition of screening for CAH to the routinely performed national neonatal screening program.