Oxidized low-density lipoprotein (oxLDL) plasma levels and oxLDL to LDL ratio — Are they real oxidative stress markers in dialyzed patients?

AimsDyslipidemia and oxidative stress are commonly present in patients during maintenance dialysis treatment. However, the significance of oxidized LDL (oxLDL) as a marker of oxidative stress in uremia is still unresolved. The aim of this study was to establish the role of oxLDL and oxLDL/LDL ratio as markers of lipoprotein abnormalities and oxidative stress in the dialyzed patients.Main methodsPlasma oxLDL level was measured by ELISA, and oxLDL/LDL ratio was calculated in 106 dialyzed patients and 20 controls. The linkages between oxLDL, oxLDL/LDL ratio and lipid profile and oxidative stress markers malondialdehyde (MDA) and Cu/Zn superoxide dismutase (Cu/Zn SOD) levels were also analyzed.Key findingsOxLDL levels and oxLDL/LDL ratio were similar in hemodialyzed patients and controls, whereas these parameters were lower in peritoneally dialyzed patients when compared to healthy individuals. In contrast, both MDA and Cu/Zn SOD levels were significantly higher in uremics than in controls. oxLDL and oxLDL/LDL ratio positively correlated with lipid profile (except of HDL), whereas there were no positive associations between these parameters and both MDA and Cu/Zn SOD. Multiple regression analysis confirmed that increased oxLDL/HDL and TC/HDL ratios and total cholesterol levels are the parameters which independently predicted oxLDL in dialyzed patients. In the case of oxLDL/LDL ratio, the independent variables were oxLDL/HDL ratio, total cholesterol and HDL levels.SignificanceoxLDL levels and oxLDL/LDL ratio seem to be the markers of lipoprotein abnormalities rather than the markers of oxidative stress in the population of dialyzed patients.