Reduced activity of 11β-hydroxylase accounts for elevated 17α-hydroxyprogesterone in preterms.

[congenital adrenal hyperplasia]

To characterize the urinary steroid metabolome of neonates and infants born either at term or preterm .We 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 ' 11 β-hydroxylase and 21 -hydroxylase activities were assessed on the basis of urinary metabolite substrate-to -product ratios .Preterm neonates and infants had elevated urinary concentrations of 17 α-hydroxyprogesterone (17 OHP ) metabolites (P <.001 ) but lower urinary concentrations of the 21 -deoxycortisol metabolite pregnanetriolone (PTO ) (P <.01 ). One reason was lower 11 β-hydroxylase activity in preterms . We could demonstrate a correlation between low 11 β-hydroxylase activity and high urinary concentrations of 17 OHP metabolites (r =0 .51 , P <.001 ) but low urinary concentrations of the 21 -deoxycortisol metabolite PTO (r =-0 .24 , P =.03 ) in preterms .Low 11 β-hydroxylase activity may explain increased 17 OHP but decreased 21 -deoxycortisol metabolite excretion in preterms . Our analysis clarifies , first , why preterms have higher 17 OHP 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 17 OHP for the diagnosis of 21 -hydroxylase deficiency .