Neonatal screening for congenital adrenal hyperplasia.

OBJECTIVE: The effectiveness of neonatal screening for reducing morbimortality in children with congenital adrenal hyperplasia (CAH) is the main justification for its implementation. One of the challenges for its implementation is to determine the cutoff value for laboratory measurement of 17-hydroxyprogesterone (17OHP) with appropriate cost-effectiveness. This study identified factors affecting the results of the pilot project of newborn screening for CAH, performed in the state of Minas Gerais, Brazil.

METHODS: Neonatal screening performed between September, 2007 and May, 2008, with 17OHP measurements performed in blood samples taken from the heel (filter paper), on the 5(th) day of life, processed by the UMELISA 17-OH Progesterona NEONATAL(®) method. The cutoff value was 80 and 160 nmol/L for healthy children or not, respectively.

RESULTS: The incidence of CAH was 1:19,939 in 159,415 children screened. The 99(th) percentile (p99) of 17OHP in the first sample was 108 nmol/L. In 13,298 newborns whose weight had been reported, the p99 of 17OHP were, respectively: 344 nmol/L for weight < 1,500 g; 260 nmol/L for weight between 1,500 and 1,999 g; 221 nmol/L for weight between 2,000 and 2,499 g; 109 nmol/L for weight ≥ 2,500g. The rate of recall for medical consultation was 0.31%. The test sensitivity was 100%, specificity was 99.6%, and the positive predictive value was 2.2%. By adjusting the cutoff values of 17OHP to 110 nmol/L and 220 nmol/L, a 76% decrease in consultation referrals was projected.

CONCLUSION: The use of 17OHP cutoff values, considering birth weight, was a cost-effective measure to reduce false positives. The results of this pilot study suggest that screening for CAH might benefit the pediatric population.