Intra-Person Variation of Urinary Biomarkers of Oxidative Stress and Inflammation

Background: Oxidative stress and inflammation have been linked to many chronic diseases including cancer and cardiovascular diseases. Urinary levels of F-2-isoprostanes (F-2-IsoPs), 2,3-dinor-5,6-dihydro-15-F(2)t-IsoP (15-F(2)t-IsoP-M), a major metabolite of F-2-IsoPs, prostaglandin E-2 metabolite (PGE-M), and leukotriene E-4 (LTE4) have been proposed as biomarkers for oxidative stress and inflammation. However, little information is available regarding the intra-person variation of these biomarkers, hindering their application in epidemiologic studies. Methods: We evaluated the intra-person variation of these four urinary biomarkers among 48 randomly chosen participants of a validation study of a population-based cohort, the Shanghai Men's Health Study. Four spot urine samples, collected during each season over a 1-year period, were measured for these biomarkers. Results: The intraclass correlation coefficients for F-2-IsoPs, 15-F(2)t-IsoP-M, PGE-M, and LTE4 were 0.69, 0.76, 0.67, and 0.64, respectively. The Spearman correlation coefficients, derived by using bootstrap analysis of single spot measurements and the average of the other three seasonal measurements, were 0.47, 0.60, 0.61, and 0.57 for F-2-IsoPs, 15-F(2)t-IsoP-M, PGE-M, and LTE4. Except for high correlations between F-2-IsoPs and 15-F(2)tIsoP-M (r = 0.65), the other biomarkers were moderately correlated (r = 0.21-0.44). Conclusions: Our study results suggest that these four urinary biomarkers have relatively low intra-person variation over a 1-year period. Impact: Spot measurements of F-2-IsoPs, 15-F(2)t-IsoP-M, PGE-M, and LTE4 could be useful as biomarkers of oxidative stress and inflammation status for epidemiologic studies. Cancer Epidemiol Biomarkers Prev; 19(4); 947-52. (C) 2010 AACR.