Evidence of an Increased Susceptibility to Lipid Peroxidation in Red Blood Cells of Chronic Renal Failure Patients

Amparo Miguel Sosa, Hospital General de Valencia, Servicio de Hematología, Avenida Tres Cruces s.n., E-46008 Valencia (Spain) Dear Sir, The study of the red blood cells (RBC) oxidative metabolism in chronic renal failure (CRF), has recently become of interest, and until now, the results have not been very concordant. It has been shown [1], that there is an alteration in RBC pentose-phosphate shunt of patients with CRF undergoing hemodialysis. This would mean an alteration in the detoxification of the hydroxyl and peroxide radicals, with the ensuing peroxidation of the polyunsaturated fatty acids (PUFA) in the RBC membranes [2]. Consequently, an increase in the rigidity and deformability of these membranes is produced and, as a result, an increase in the susceptibility to hemolysis appears. The malonyl-dialdehyde acid (MDA), a short-chain aldehyde, is an intermediate product of the oxidation of PUFA, and has been reported as a good indirect method to measure the oxidative degradation of PUFA [3,4]. In order to investigate the susceptibility to the oxidative damage in the RBC, we determined the RBC levels of MDA in a group of patients affected by CRF. The study was performed on 58 subjects with CRF, divided into two groups. Group I consisted of 30 patients, 16 males and 14 females, aged 39–82 years (mean 62). The creatinine clearance was lower than 15 ml/min, (preterminal renal failure). All of them followed a low-protein and low-salt diet, adapted to tension levels. Group II consisted of 28 patients, 24 males and 4 females, aged 22–74 years (mean 51). All these patients were subjected to a regular hemodialysis program with a mean treatment duration of 37.3 months (range 27–150). The patients were dialyzed three times weekly, each session lasting 4 h. The dialyses were all done with a 0.9to 1.3-m2 hollow-fiber dialyzer and a standard dialysate with an acetate concentration of 38 mEq/1, and a dialysate flow rate of 500 ml/min. Water was purified by an inversed-osmosis treatment. All patients were on a free diet, and none of them were taking any drugs that could interfere with the parameters considered, nor had they received any blood transfusion during the 3 months preceding the study. Patients presenting hepatic