Within-subject variation of plasma resistin levels over a 1-year period

Background: Resistin, a recently discovered hormone, is purportedly involved in metabolic and inflammatory processes in humans and may thus be an important marker to assess disease risk in large-scale epidemiological studies. Methods: We assessed the reliability of human resistin levels in 63 men and 51 women aged 35-67 years with repeated measurements of resistin over a period of 1 year. Student's paired t-test was used to compare resistin concentrations at baseline and 1 year later. Intraclass correlation coefficients (ICCs) were calculated by analysis of variance. Results: There was no significant difference between resistin concentrations at baseline and after 1 year for both sexes combined or when analyzed separately for men and women. The ICCs were 0.70 (95% Cl 0.59-0.78) for both sexes combined, 0.75 (95% Cl 0.62-0.84) for men, and 0.66 (95% Cl 0.47-0.79) for women. Resistin levels were not significantly related to age, body mass index, waist-to-hip ratio, sex, or fasting status. Conclusions: Individual blood resistin concentrations did not significantly change over a period of 1 year, but showed a high degree of reliability. Our findings suggest that a single resistin measurement may be sufficient for risk assessment in epidemiological studies.