Spectrophotometric Determination of Malondialdehyde in Urine Suitable for Epidemiological Studies

A reliable method for spectrophotometric determination of urinary malondialdehyde (MDA), according to the thiobarbituric acid (TBA) assay, is described. To account for matrix interference and differences in individual urine composition, standard addition procedure was applied. The method is adequately selective (LoQ = 0.09 mu M in the presence of 0.1 M creatinine and 0.5 M urea) and reliable (within-day and between-day variability of less than 5 %). The mean level of urinary MDA was 1.52 +/- 0.73 mu M that is in good agreement with spectrofluorometric determination (1.20 +/- 0.56 mu M; p = 0.085) as well as with previous studies that used HPLC. Furthermore, it is demonstrated that MDA is stabile in urine at room temperature for 24 h and when stored at -20 degrees C for 6 months. The described method enables simple, rapid and cost-effective determination of urinary MDA as a relevant and non-invasive marker of whole-body oxidative stress.