Within-Individual Stability of Obesity-Related Biomarkers among Women

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Abstract
Objective: Novel biomarkers including proinflammatory cytokines and adipokines are being explored as potential mediators of cancer and other obesity-related conditions. Prospective studies linking biomarker levels with disease outcomes often measure biomarkers at a single time point and assume that the within-individual variation in levels is small compared with the interindividual variation. However, this assumption is seldom tested. Methods: This study examined the within-individual stability over time of plasma adiponectin, resistin, leptin, plasma activator inhibitor type 1, hepatocyte growth factor, tumor necrosis factor α, interleukin 6, and insulin among healthy young women. Results: The study included 17 women (9 Black non-Hispanic, 2 Black Hispanic, 2 White Hispanic, and 4 other race/ethnicity) with mean age of 32.3 years, mean body mass index of 31.2 kg/m2, and 76% prevalence of smoking. Analysis of intraclass correlation (ICC) suggested high to moderate correlation over repeated samples taken over 3 years in levels of resistin (ICC = 0.95), hepatocyte growth factor (0.91), plasma activator inhibitor type 1 (0.84), adiponectin (0.73), insulin (0.62), and leptin (0.58). ICCs were weaker for levels of proinflammatory cytokines, tumor necrosis factor α (0.39), and interleukin 6 (0.47). Conclusion: In this population of minority young females with a high prevalence of overweight and smoking, several obesity-related endocrine markers were stable over a period of 3 years. This supports the feasibility of longitudinal studies relating these biomarkers to the future occurrence of cancer and other health consequences of obesity. (Cancer Epidemiol Biomarkers Prev 2007;16(6):1291–3)