Plasma 21-deoxycortisone: a sensitive additive tool in 21-hydroxylase deficiency in newborns.

OBJECTIVE, DESIGN, AND METHODS: Although 17-hydroxyprogesterone (17OHP) has historically been the steroid assayed in the diagnosis of congenital adrenal 21-hydroxylase deficiency (CAH-21D), its C11-hydroxylated metabolite, 21-deoxycortisol (21DF), which is strictly of adrenal origin, is assayed in parallel in this pathology. This steroid (21DF) is oxidized by 11beta-hydroxysteroid dehydrogenase type 2 into 21-deoxycortisone (21DE). In the context of CAH-21D confirmation testing, confounding factors (such as intensive care unit admission, stress, prematurity, early sampling, and variations of sex development) can interfere with the interpretation of the gold-standard biomarkers (17OHP and 21DF). Since its tissue concentrations are especially high in the placenta, we hypothesized that 21DE quantification in the neonatal periods could be an interesting biomarker in addition to 17OHP and 21DF. To verify this hypothesis, we developed a new mass spectrometry-based assay for 21DE in serum and applied it to newborns screened for CAH-21D. RESULTS: In newborns with CAH-21D, the mean serum levels of 21DE reached 17.56 ng/mL (ranging from 8.58 ng/mL to 23.20 ng/mL), and the mean 21DE:21DF ratio was 4.99. In contrast, in newborns without CAH-21D, the 21DE serum levels were low and not statistically different from the analytical 21DE limit of quantification (0.01 ng/mL). CONCLUSION: Basal serum 21DE appears to be a novel sensitive and specific biomarker of CAH-21D in newborns.