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Reproducibility of Serum Leptin, Insulin-Like Growth Factor-I, and Insulin-Like Growth Factor-Binding Protein-3 MeasurementsChia V.M.a, b · Newcomb P.A.a, b · White E.a, b · Zheng Y.a · Potter J.D.a, b · Lampe J.W.a, b
aCancer Prevention Program, Fred Hutchinson Cancer Research Center, and bDepartment of Epidemiology, University of Washington, Seattle, Wash., USA
Background: Many epidemiologic studies examine the effects of single measurements of hormones, including those related to obesity such as insulin-like growth factors (IGFs) or leptin, on disease associations; however, few studies have determined whether these single values accurately reflect measurements over time. Methods: We examined the reproducibility of hormones associated with obesity, specifically leptin, IGF-I, and IGF-binding protein-3 (IGFBP-3). Two fasting blood samples, approximately four months apart, were collected from 38 participants from the Seattle metropolitan area; leptin, IGF-I, and IGFBP-3 concentrations were measured in previously unthawed serum samples. Unadjusted and adjusted intraclass correlation coefficients (ICC) were calculated to assess reproducibility. Results: Adjusting for age and sex, the ICCs for leptin, IGF-I, and IGFBP-3 were 0.73, 0.83 and 0.60, respectively. Weighted kappas yielded similar results. Conclusion: These data suggest that for leptin, IGF-I, and IGFBP-3, a single fasting serum measurement can fairly reliably reflect the hormonal milieu over periods of months.
© 2008 S. Karger AG, Basel