Precursortoproduct ratios reflect biochemical ph

Authors: Rebecca A Hicks Jennifer K Yee Catherine S Mao Steve Graham Martin Kharrazi Fred Lorey W P Lee

Publish Date: 2013/06/23

Volume: 10, Issue: 1, Pages: 123-131

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Abstract

Precursortoproduct ratios in steroid hormone metabolism may accurately reflect enzymatic activity and production of metabolites relative to their disappearance The purpose of this study was to explore the use of direct precursortoproduct steroid ratios to discriminate between infants with congenital adrenal hyperplasia CAH due to 21αhydroxylase deficiency and infants with no disorder thus characterizing the biochemical phenotype in CAH Deidentified dried blood spot samples from confirmed CAH cases identified by newborn screen CAHpositive N = 8 and from cases with no disorder CAHnegative N = 10 were obtained from the California State Newborn Screening Program Samples ~625 mm circular spots underwent methanol and water extraction 91 ratio Deuterated steroids served as isotope internal standards 17αhydroxyprogesterone 17OHP 11deoxycortisol S androstenedione A4 and cortisol F concentrations were determined by liquid chromatography–tandem mass spectrometry LC–MS/MS and the 17OHP/S 17OHP/A4 and S/F ratios were calculated The mean 17OHP and A4 concentrations in samples from CAH cases were significantly increased when compared to cases with no disorder p = 0003 for both 17OHP/S and 17OHP/A4 ratios were also significantly elevated in CAH cases p = 0007 and p  0001 respectively In contrast S and F concentrations and the S/F ratio were similar between the two groups In CAH the elevated 17OHP/S ratio is a biomarker of diminished 21αhydroxylase activity and the elevated 17OHP/A4 ratio is a biomarker of adrenal androgen excess via increased 1720lyase activity The similar S/F ratio indicates that the rate of production via 11βhydroxylase and disappearance of F is maintained in CAHWe would like to thank Maria Lajoie and Shu Lim of the CTSI Core Laboratory for their technical assistance and Seyed Sadjadi of Phenomenex for his help in optimizing the LC–MS/MS method Steroid analyses were performed at the Biomedical Mass Spectrometry facility at the Los Angeles Biomedical Research Institute at HarborUCLA which is partly supported by the University of California Los Angeles Clinical and Translational Science Institute UL1 TR000124 and the Metabolomics core of the Center of Excellence for Pancreatic Diseases P01 AT003960

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