Wisconsin’s screening algorithm for the identification of newborns with congenital adrenal hyperplasia

Newborn screening for congenital adrenal hyperplasia (CAH) has one of the highest false positive rates of any of the diseases on the Wisconsin panel. This is largely due to the first-tier immune assay cross-reactivity and physiological changes in the concentration of 17-hydroxyprogesterone during the first few days of life. To improve screening for CAH, Wisconsin developed a second-tier assay to quantify four different steroids (17-hydroxyprogesterone, 21-deoxycortisol, androstenedione, and cortisol) by liquid chromatography–tandem mass spectrometry (LC–MSMS) in dried blood spots. From validation studies which included the testing of confirmed CAH patients, Wisconsin established its own reporting algorithm that incorporates steroid concentrations as well as two different ratios—the birth weight and the collection time—to identify babies at risk for CAH. Using the newly developed method and algorithm, the false positive rate for the CAH screening was reduced by 95%. Patients with both classical forms of CAH, salt-wasting and simple virilizing, were identified. This study replicates and expands upon previous work to develop a second-tier LC–MSMS steroid profiling screening assay for CAH. The validation and prospective study results provide evidence for an extensive reporting algorithm that incorporates multiple steroids, birth weight, and collection times.