Stability of measurements of biomarkers of oxidative stress in blood over 36 hours.

Oxidative stress is hypothesized to play an important role in a variety of chronic diseases, but the short-term and long-term stability of measurements of biomarkers related to oxidative stress remains unclear. The objective of this study was to evaluate the stability of measurements of malondialdehyde (MDA), F2-isoprostanes, and fluorescent oxidation products in blood stored on ice within 36 hours until processing. Whole blood samples from six healthy women were processed at 0, 24, and 36 hours after being stored on ice. MDA was measured by the thiobarbituric acid-reactive substances assay with high-pressure liquid chromatography. F2-isoprostanes were measured by gas chromatography/mass spectrometry. The fluorescent oxidation products were measured by spectrofluorometry. Measurements of fluorescent oxidation products were very stable up to 36 hours. Intraclass correlation coefficients (ICC) were >0.95 for each time interval (0 to 24 and 0 to 36 hours). Measurements of MDA were the least stable. The median increased significantly from 0 to 24 hours and from 0 to 36 hours. The ICC for MDA for each time interval (0 to 24 and 0 to 36 hours) was <0.1. Finally, the median of F2-isoprostane measurements at each time point also increased significantly. ICCs were 0.45 for 0 to 24 hours and 0.09 for 0 to 36 hours. We conclude that measurements of fluorescent oxidation products in blood remain stable for up to 36 hours and may be used in large prospective epidemiologic studies of chronic diseases.