Nephrol Dial Transplant (2001) 16: 1626-1630
© 2001 European Renal Association-European Dialysis and Transplant Association
Oxidant stress in nephrotic syndrome: comparison of F2-isoprostanes and plasma antioxidant potential
1 Department of Medicine and Western Australian Heart Research Institute, University of Western Australia, and 2 Department of Nephrology, Royal Perth Hospital, Perth, Western Australia
Background. The nephrotic syndrome (NS) is associated with an increased risk of coronary heart disease. Increased oxidant stress may contribute to this by means of hyperlipidaemia and/or hypoalbuminaemia. In this study we assessed the contributory role of oxidant stress, as measured by F2-isoprostanes and plasma oxygen radical absorbance capacity (ORAC), in subjects with NS.
Methods. We studied 14 subjects with NS and 17 age- and sex-matched healthy non-proteinuric controls. Measurement of plasma and urinary F2-isoprostanes was carried out using a combination of silica and reverse-phase cartridges, high-performance liquid chromatography, and gas chromatography mass spectrometry using electron-capture negative ionization. The plasma ORAC assay measured the decrease in fluorescence of phycoerythrin added to plasma in the presence of a free-radical generator. The ORAC value (µM) was calculated as the ratio of the area under the fluorescence decay curve for plasma to the area under the fluorescence decay curve for a Trolox standard.
Results. Plasma ORAC was significantly lower in NS patients compared with controls: mean (standard error) NS patients 3306 µM (286); controls 4882 µM (496), P=0.011. In univariate linear regression analysis, plasma albumin was significantly positively correlated with plasma ORAC (r=0.40, P=0.03). Plasma and urinary F2-isoprostanes did not differ significantly between NS and control groups.
Conclusions. This study demonstrates that in the NS there is decreased free-radical trapping capacity of plasma that is inversely correlated with hypoalbuminaemia, but no increase in plasma and urinary F2-isoprostanes. Decreased total plasma antioxidant potential in combination with hyperlipidaemia may contribute to the increased risk of cardiovascular disease seen in NS.
Keywords: anti-oxidant defence; dyslipidaemia; F2-isoprostanes; nephrotic syndrome; oxidant stress; oxygen radical absorbance capacity (ORAC)
Correspondence and offprint requests to: Dr G. Dogra, University Department of Medicine, Royal Perth Hospital, Box X2213 GPO, Perth, Western Australia 6001, Australia.