Glutathione, glutathione-related enzymes, and total antioxidant capacity in patients on maintenance dialysis

Oxidative stress due to overproduction of reactive
oxygen species and impairment in antioxidant defense mechanisms
have been suggested as possible factors contributing to the
pathogenesis of atherosclerosis in patients with end-stage renal
disease. We compared glutathione levels, glutathione peroxidase
and glutathione reductase activities, and total antioxidant capacity
between patients on hemodialysis and peritoneal dialysis and
healthy individuals.
Materials and Methods. Thirty patients receiving regular
hemodialysis and 12 on continuous ambulatory peritoneal dialysis
were recruited as well as 25 healthy volunteers. Diabetes mellitus,
recent febrile or infectious episodes, and hospitalization during
the past month were the exclusion criteria. Erythrocyte glutathione
level, plasma activities of glutathione peroxidase and glutathione
reductase, total antioxidant capacity were determined and compared
between the three studied groups.
Results. Glutathione levels and glutathione peroxidase activity
were markedly lower in the patient groups than in the controls.
Conversely, higher activity of glutathione reductase and total
antioxidant capacity were noted in the patients than in the controls.
There were no significant differences between antioxidant markers
of the patients on hemodialysis and peritoneal dialysis. Strong
positive correlation were observed between total antioxidant
capacity and uric acid in the patients (r = 0.59, P = .045 and
r = 0.63, P = .03, respectively).
Conclusions. Although total antioxidant capacity of plasma is
increased in patient on dialysis, depletion of glutathione as a key
antioxidant component and disturbances in its related enzymes
show oxidative stress. This condition may increase the risk of
developing cardiovascular disease in patients with end-stage
renal disease.