Marker of lipid peroxidation related to diabetic nephropathy in Indonesian type 2 diabetes mellitus patients.

OBJECTIVE: Even though diabetes patients exhibit an increased oxidative stress, its correlation with diabetic nephropathy is not fully understood. The purpose of this study was to determine whether lipid peroxidation marker correlates well with eGFR and UACR in type 2 diabetes mellitus patients. METHODS: We collected urine and serum samples of Indonesian type 2 diabetes mellitus outpatients with normo- and microalbuminuria at a Local Government Clinic (from ages: 39-74 years). Urinary 8-iso-PGF2α was measured by ELISA, the serum malondialdehyde by TBARS assay, and urinary albumin by BCG albumin assay. eGFR was calculated using the corrected-Cockcroft-Gault (CG), MDRD, and CKD-EPI equation. Other necessary data were obtained through questionnaires. RESULTS: The results showed that the increasing level of malondialdehyde was mildly correlated with the decline in eGFR (MDRD). In contrary, there was a significant positive correlation between 8-iso-PGF2α concentration and eGFR based on the corrected-CG, MDRD study, and CKD-EPI equation (r=0.457, p<0.001; r=0.424, p<0.001; r=0.443, p<0.001). This relationship still persisted in the normoalbuminuric subjects (n=43) (r=0.491, p=0.001; r=0.461, p=0.002; r=0.455, p=0.002). The multivariate analysis showed that 8-iso-PGF2α together with fasting plasma glucose was the most predictive factor for the high 2-quantile eGFR (adjusted OR 1.001, (95% CI, 1.000-1.001)). However, there was no significant correlation between UACR with malondialdehyde (r=0.268, p=0.050) and 8-iso-PGF2α(r=-0.030, p=0.808). UACR itself was inversely correlated with eGFR based on the corrected-CG, the MDRD, and CKD-EPI (r=-0.232, p<0.05; r=-0.228, p<0.05; r=-0.232, p<0.05). CONCLUSIONS: Increased 8-iso-PGF2α and malondialdehyde in type 2 diabetes mellitus patients may play a role in the pathophysiologic significance of diabetic nephropathy, even while considering the effect of potential confounders.

Evaluation of urinary hydrogen peroxide as an oxidative stress biomarker in a healthy Japanese population.

The usefulness of urinary hydrogen peroxide (H(2)O(2)) as an oxidative stress biomarker was evaluated in 766 healthy Japanese. The mean level of urinary concentrations of H(2)O(2) was 5.66 ± 8.27 µmol/g creatinine, and was significantly higher in females than in males. Significant correlations of H(2)O(2) were observed with age, aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), insulin, 8-hydroxy-2'-deoxyguanosine (8-OHdG), and exercise habit in females. In both sexes, H(2)O(2) showed a significant correlation with 8-OHdG. By a multiple logistic regression analysis, urinary H(2)O(2) was positively associated with urinary 8-OHdG and TC and was inversely associated with insulin. By stratification of sex and age, the association of urinary H(2)O(2) with TC was positive in both sexes under 50 years old and was inverse in males over 50 years old, and that with insulin was inverse in males over 50 years old and in females under 50 years old. Moreover, by stratification of sex and age, a positive association of H(2)O(2) with exercise and an inverse association of H(2)O(2) with alcohol consumption became clear in males under 50 years old, although there were no significant odds for H(2)O(2) after adjustment for covariates. In conclusion, the present results suggest that urinary H(2)O(2) is a useful biomarker for oxidative stress, showing an association with 8-OHdG, TC, and insulin independently.