IMPE Abstracts

The primary goals of newborn screening (NBS) for congenital adrenal hyperplasia (CAH) are the prevention of life-threatening salt-wasting crisis in the most severe forms. NBS for CAH from dried blood spots has been implemented in several countries. An increased 17-hydroxyprogesterone (17OHP) concentration in heel-prick blood is used to indicate patients at risk of having CAH. However, compared with the detection of other diseases by NBS, CAH screening is associated with a high frequency for the false positive. One of the reasons is the cross-reactivity with other steroids secreted from the feal adrenal. Another reason is that preterm infants actually have elevated levels of 17-OHP due to stress. Several studies have shown that positive predictive value can be increased by using steroid analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) as a second-tier test. We measured 21-deoxycortisol (21DOF), androstenedione (4AD), cortisol (F), and 11-deoxycortisol (11DOF) and we set the algorithm of NBS by adding 11DOF/17OHP in addition to 21DOF and 17-OHP+4AD/F. As results, compared to the period when 17-OHP was measured by ELISA and a cut-off value was set, the number of neonates requiring recall decreased from 3.5% to 0.042%. At the same time, the positive predictive value was increased from 55% to 75%. These results demonstrate that it is more useful to use 11DOF/17OHP as cutoff values in addition to 21DOF and 17-OHP+4AD/F as a second-tier test.