Epidemiological marker for oxidant status:: Comparison of the ELISA and the gas chromatography/mass spectrometry assay for urine 2,3 dinor-5,6-dihydro-15,F2t-isoprostane

PURPOSE: A biomarker of oxidant status applicable to epidemiological research is essential to studying the relationship between free radicals and chronic disease risk. Gas chromatography with mass-spectrometry detection (GC/MS) is the gold standard for measurement of urinary F-2-isoprostanes (F-2-isoPs), a noninvasive marker of oxidant status. However, this method is laborious and costly, which prohibits its use in large epidemiological studies. METHODS: We compared GC/MS assay with an inexpensive quick enzyme-linked immunoassay (ELISA) in measurements of 2,3-dinor-5,6-dihydro-15-F-2t-isoprostane (F-2-isoPM), an abundant beta-oxidation metabolite of 8-iso-prostaglandin-F-2alpha. We measured F-2-isoPM in urine of 52 participants of the Insulin Resistance Atherosclerosis Study by both methods. RESULTS: The ELISA measurements showed approximately 30-fold greater mean and median (22.10, SD 12.92, and 18-49 ng/mg creatinine) than the GC/MS measurements (0.703, SD 0.468, and 0.597 ng/mg creatinine). We found low linear correlation (Pearson correlation coefficient 0.51; 95% CI, 0.28-0.70) and weak agreement in ranking subjects by tertiles (weighted Kappa statistic 0.34) between a GC/MS and ELISA. CONCLUSIONS: We conclude that the current ELISA method is not a valid substitute for the GS/MS assay. (C) 2004 Elsevier Inc. All rights reserved.