Reduced Activity of 11β-Hydroxylase Accounts for Elevated 17α-Hydroxyprogesterone in Preterms

ObjectiveTo characterize the urinary steroid metabolome of neonates and infants born either at term or preterm.Study designWe retrospectively analyzed urinary steroid hormone metabolites determined by gas chromatography–mass spectrometry of 78 neonates and infants born at term and 83 neonates and infants born preterm (median 34 weeks of gestational age). The subjects' 11β-hydroxylase and 21-hydroxylase activities were assessed on the basis of urinary metabolite substrate–to–product ratios.ResultsPreterm neonates and infants had elevated urinary concentrations of 17α-hydroxyprogesterone (17OHP) metabolites (P < .001) but lower urinary concentrations of the 21-deoxycortisol metabolite pregnanetriolone (PTO) (P < .01). One reason was lower 11β-hydroxylase activity in preterms. We could demonstrate a correlation between low 11β-hydroxylase activity and high urinary concentrations of 17OHP metabolites (r = 0.51, P < .001) but low urinary concentrations of the 21-deoxycortisol metabolite PTO (r = −0.24, P = .03) in preterms.ConclusionsLow 11β-hydroxylase activity may explain increased 17OHP but decreased 21-deoxycortisol metabolite excretion in preterms. Our analysis clarifies, first, why preterms have higher 17OHP levels and thus higher rates of false-positive screening results for congenital adrenal hyperplasia than do term infants, and, second, why 21-deoxycortisol or its urinary metabolite PTO is more specific than 17OHP for the diagnosis of 21-hydroxylase deficiency.