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

ABSTRACT

OBJECTIVE: To characterize the urinary steroid metabolome of neonates and infants born either at term or preterm. STUDY DESIGN: 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' 11ß-hydroxylase and 21-hydroxylase activities were assessed on the basis of urinary metabolite substrate-to-product ratios. RESULTS: Preterm 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 11ß-hydroxylase activity in preterms. We could demonstrate a correlation between low 11ß-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. CONCLUSIONS: Low 11ß-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.