Protein thiol oxidation and lipid peroxidation in patients with uraemia

Background: Patients with uraemia are exposed to increased oxidative stress. In this study, a series of oxidative stress markers were measured in patients with chronic renal failure (CRF) and patients with CRF on haemodialysis (HD) compared to normal controls to establish whether there is enhanced oxidative stress on HD therapy in uraemic subjects. Methods: Protein thiol oxidation, lipid hydroperoxides, albumin and uric acid concentrations were estimated in patients receiving HD and patients with CRF and compared with those in healthy controls. Results: There was a significant decrease in the level of protein thiols in CRF (p = 0.0001) and HD patients (p = 0.0001) compared with that in controls. Lipid hydroperoxides were significantly higher in CRF (p = 0.026) and HD patients (p = 0.003) than in controls. However, there was no significant difference in protein thiols and lipid hydroperoxides between CRF and HD patients. Serum protein thiols correlated negatively with lipid hydroperoxides and positively with serum albumin. Conclusions: These findings suggest that both CRF and HD patients have increased plasma protein oxidation and lipid peroxidation. However, HD therapy per se did not contribute to oxidative stress already present in uraemia. Owing to the variability in lipid peroxidation products as markers of oxidative stress and the vital role played by thiol antioxidants in the biological system, it is suggested that protein thiol oxidation may be a better marker of oxidative stress.