Stability and reliability of plasma level of lipid biomarkers and their correlation with dietary fat intake.

The reliability and stability of plasma lipid biomarkers and their association with dietary fat intake were evaluated among 48 subjects who were randomly chosen from the participants of a validation study of the population-based cohort, the Shanghai Men's Health Study (SMHS). Four spot blood samples, one taken each season, were measured for total cholesterol, triglyceride, HDL-cholesterol, and LDL-cholesterol levels. The reliability and stability of these measurements were assessed by intraclass correlation coefficients (ICC) and by the correlations between a randomly chosen measurement with the mean of measurements across seasons using a bootstrap approach. The median levels for total cholesterol, triglycerides, HDL-cholesterol, and LDL-cholesterol were 177.5, 164.5, 41.0, and 102.5 (mg/dl), respectively. The ICCs of the biomarkers ranged from 0.58 (LDL-cholesterol) to 0.83 (HDL-cholesterol). The correlation between randomly chosen spot measurements and the mean measurement were 0.91, 0.86, 0.93, and 0.83 for total cholesterol, triglycerides, HDL-cholesterol, and LDL-cholesterol, respectively. The correlations of lipid biomarkers with dietary fat intake and other lifestyle factors were comparable to other previous reports. In conclusion, this study suggests that measurements of lipid biomarkers from a single spot blood sample are a good representation of the average blood levels of these biomarkers in the study population and could be a useful tool for epidemiological studies.