OXIDATIVE STRESS AND ANTIOXIDANT DEFENSES IN RENAL PATIENTS RECEIVINGREGULAR HEMODIALYSIS

Patients with chronic renal failure, and particularly those receiving regular haemodialysis, have a high incidence of premature cardiovascul ar disease. Oxidative stress, which causes lipid peroxidation, may con tribute to increase the risk of atherosclerosis. The results of the pr esent study indicate that lipid peroxidation products (malonaldehyde a nd 4-hydroxyalkenals) are significantly increased in plasma of renal p atients before dialysis and, although reduced, remained above the norm al range after this treatment. Moreover, production of free radicals a nd reactive oxygen metabolites was increased in chronic renal failure patients, especially after dialysis. On the other hand, the antioxidan t defenses of those patients were higher than those of normal subjects , as judged from the plasma levels of specific antioxidant molecules a nd from the plasma antioxidant capacity. We also found that triglyceri des were significantly higher in renal patients, both before and after dialysis, than in the control group. These results suggest that patie nts on chronic haemodialysis are particularly prone to oxidative stres s and that dialysis itself may worsen this condition. Rather than to a weakening of antioxidant defenses, the susceptibility of chronic rena l failure patients to oxidative stress might be ascribed to an increas ed free radical and reactive oxygen metabolite production and to incre ased levels of oxidizable substrates, notably triglycerides with their unsaturated fatty acids.