Lipid peroxidation and antioxidant enzymes in children with chronic renal failure

Increased lipid peroxidation (LP) has been observed in dialysis patients and in predialysis adults with advanced chronic renal failure (CRF). The aim of this study was to investigate whether predialysis CRF children have increased LP in plasma and red blood cells (RBC) and to evaluate the activity of the antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px)] in RBC. Concentrations of selenium (Se), copper (Cu), and zinc (Zn)—cofactors of these enzymes—were determined both in erythrocytes and in plasma. LP was monitored by plasma and erythrocyte malonyldialdehyde (MDA) and by plasma organic hydroperoxide (OHP) concentrations. Forty-six predialysis children, aged 5–18 years, divided into two groups according to their serum creatinine levels [group I (n=14, mean serum creatinine 421.61±141.08 μmol/l), group II (n=32, mean serum creatinine 174.94±45.50 μmol/l)] and 27 age-matched healthy subjects were enrolled in the study. Significantly higher concentrations of plasma and erythrocyte MDA and plasma OHP, significantly lower activities of GSH-Px and CAT, and significantly lower concentrations of erythrocyte Se, Cu, and Zn and plasma Se and Cu were found in both groups of renal patients compared with controls. The SOD activity was reduced in both groups of CRF children. In group I the activity of SOD and GSH-Px was significantly lower than in group II. In summary, there is increased LP in plasma and RBC in children with predialysis CRF, even those patients with moderate renal insufficiency. The activity of the enzymatic antioxidant defense system is reduced in the RBC of predialysis patients. The antioxidant capacity is related to the severity of renal failure.