A study of plasmalogen as an index of oxidative stress in patients with chronic renal failure. Evidence of increased oxidative stress in malnourished patients

Background. The incidence of premature cardiovascular disease is high in patients with chronic renal failure (CRF). Free-radical-induced tissue damage is thought to play a major role in the pathogenesis of atherosclerosis and several reports indicate increased oxidative stress in patients with CRF. However, the cause of such stress in CRF is not exactly known. Plasmalogens, a group of phospholipids with a vinyl ether bond in the sn-1 position, are supposed to be sensitive markers of oxidative stress. Methods. The fasting relative plasmalogen levels of erythrocyte membranes (DMA 16/C16:0 and DMA 18/C18:0), as well as of vitamin E and serum lipids, were determined in a cohort of 105 patients (mean age 51+/-2 years) with advanced CRF (creatinine clearance 9+/-1 ml/min) before starting dialysis treatment. Twenty-nine healthy controls (47+/-2 years) were also investigated. Results. Significantly lower relative plasmalogen levels (DMA 16/C16:0 and DMA 18/C18:0)were found in erythrocytes of predialysis patients than in controls. When the patients were divided on the basis of subjective global assessment of nutritional status (SGA), the malnourished patients (SGA 2-4) had significantly (P<0.05) lower relative plasmalogen levels than the well-nourished predialysis patients (SGA 1). In the prospective part of the study, we found that a 12-month dialysis treatment in 38 patients was associated with significant increases in both erythrocyte DMA 16/C16:0 (P<0.001) and DMA18/C18:0 (P<0.05) ratios. Conclusion. The present results suggest that predialysis patients are exposed to an augmented oxidative stress which is partially reversed by 12 months of dialysis treatment. The present study also demonstrates lower relative plasmalogen levels in erythrocyte membranes in malnourished than in well-nourished predialysis patients. One could speculate that an increased oxidative stress may be a factor contributing to the high prevalence of cardiovascular disease documented in malnourished CRF patients.