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Congenital adrenal hyperplasia (CAH) is primarily caused by 21-hydroxylase deficiency and leads to an accumulation of 17-hydroxyprogesterone and reduced cortisol levels. Newborn screening for CAH is traditionally based on measuring 17-hydroxyprogesterone by different immunoassays. Despite attempts to adjust cutoff levels for birth weight, gestational age, and stress factors, the positive predictive value for CAH screening remains less than 1%. To improve this situation, we developed a method using liquid chromatography-tandem mass spectrometry to measure 17-hydroxyprogesterone, androstenedione, and cortisol simultaneously in blood spots. A total of 1222 leftover blood spots from six different screening programs using different immunoassays (fluorescent immunoassay and ELISA) were reanalyzed in a blinded fashion by liquid chromatography-tandem mass spectrometry. Thirty-one samples were from babies with CAH, 190 had yielded false-positive results by immunoassay, and the remaining 1001 samples were from babies with normal screening results. Steroid profiling allowed for an elimination of 169 (89%) of the false-positive results and for an improvement of the positive predictive value from the reported 0.5 to 4.7%. Although this method is not suitable for mass screening due to the length of the analysis (12 min), it can be used as a second-tier test of blood spots with positive results for CAH by the conventional methods. This would prevent unnecessary blood draws, medical evaluations, and stress to families.

Steroid Profiling by Tandem Mass Spectrometry Improves the Positive Predictive Value of Newborn Screening for Congenital Adrenal Hyperplasia