Session: FP11-Pediatric Endocrinology
Room 104 (Moscone Center)
Poster Board SAT-601
Methods: Deidentified dried blood spot samples from confirmed CAH cases identified by newborn screen (N=8) and second-tier samples (N=197) were obtained from the California State Newborn Screening Program with the approval of the Institutional Review Board. Samples (~6.25 mm circular spots) were extracted and processed using methanol:water in the ratio of (9:1). Deuterated steroids were added to each sample before extraction as isotope internal standards. 17-OHP, 11-deoxycortisol (11-DOC), androstenedione (A4) and cortisol in the blood spots were quantified using liquid chromatography-tandem mass spectrometry. The 17-OHP/11-DOC and 17-OHP/A4 ratios were calculated.
Results: 17-OHP/11-DOC >1.6 (Pd) and 17-OHP/A4 >2 (Pa) in CAH-positive samples reflect diminished 21-α-hydroxylase activity and elevated androgen production. Using these ratios as criteria for decreased cortisol and increased adrenal androgen production, the second-tier samples were classified into four groups according to Pd, Pa, Nd (17-OHP/11-DOC <1.6) and Na (17-OHP/A4 <2). The proportions of adrenal profiles differed by birth weight (BW) greater or less than 1500 grams, with χ2(3, N = 197) = 83.38, p <0.001.
Conclusion: Steroid profiles of second-tier samples are clearly dependent on birth weight categories. Infants with BW <1500 had an androgen (A4)-producing phenotype associated with elevated 17-OHP, contributing to many false positives by the second-tier criteria. For infants with BW >1500, additional criteria based on 17-OHP/11-DOC and 17-OHP/A4 ratios may be helpful to further reduce the false positive rate in newborn screening of CAH.
Nothing to Disclose: RAH, JKWY, CSM, MK, SG, FL, WNPL
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