ESPE Abstracts (2019) 92 P1-5

18 years of neonatal screening for congenital adrenal hyperplasia in North-Eastern Italy: recall rate reduction thanks to liquid chromatograpy-tandem mass spectrometry as second tier test

paolo cavarzere, Laura Palma, Silvana Lauriola, Rossella Gaudino, Monica Vincenzi, Francesca Teofoli, Franco Antoniazzi, Marta Camilot


Pediatric Division, Department of Pediatrics, University Hospital of Verona, Verona, Italy


Background: In North-Eastern Italy, a newborn screening for congenital adrenal hyperlpasia (CAH) has been taking place since 2001 to diagnose the classical form of 21-hydroxylase deficiency (21-OHD). Thanks to the screening program based on 17-OHP levels in dried blood spots, early diagnosis of CAH is possible, allowing appropriate precocious treatment and reducing mortality rates. Unfortunately, a high false positive rate, especially in preterm, low-birth-weight and critically ill newborns, is described.

Aims: The aims of our study are to summarize the results of the newborn screening for CAH held in the last eighteen years in North-Eastern Italy and to evaluate the diagnostic utility of simultaneous determination of 17-OHP, cortisol, 11-deoxycortisol, delta 4-androstenedione and 21-deoxycortisol by liquid chromatograpy-tandem mass spectrometry (LC-MS/MS) as second tiers performed on the same blood spot.

Materials and Methods: Since 2001 dried blood spots from newborns have been screened with a time-resolved fluoroimmunoassay method (DELFIA) for 17-OHP determination. Over the years, the cutoff levels of 17OHP were adjusted according to gestational age. Since 2017, samples resulted above the cutoff have been immediately analyzed by LC-MS/MS in order to differentiate affected patients from false positive newborns.

Results: Since 2001, 786.302 newborns have been screened, with 34 diagnosis of classic form of 21-OHD and a total incidence of 1:23126. To date, we have no information about false negative cases (sensitivity of 100%). Over the years, adjustments of cutoff values for 17-OHP based on gestational age and, in particular, the use of LC-MS/MS, as a second-tier test for positive CAH screening significantly reduced the recall rate (RR). RR varied by a maximum value of 1.06 in 2009 to 0.85 in 2016 before LC-MS/MS, and reached the value of 0.45 in 2017 and of 0.17 in 2018 after the introduction of LC-MS/MS.

Conclusions: The screening for CAH proved to be useful in the neonatal diagnosis of classic form of 21-OHD, allowing a precocious and appropriate treatment, significantly reducing mortality as well. Moreover, the use of LC-MS/MS as a second tier test resulted in a useful tool to improve the positive predictive value of the screening program. LC-MS/MS is not suitable to replace the conventional method, but it is extremely useful as a second-tier test in particular in preterm, low-birth-weight and critically ill neonates, preventing unnecessary blood draws, medical evaluations and stress to families.