Oxidative Stress in Hemodialysis Patients: Pathophysiological Mechanisms, Clinical Consequences and Basic Principles of Treatment

Erythropoietin Resistance Development in Hemodialysis Patients: The Role of Oxidative Stress

Oxidative stress (OS) is considered a significant risk factor for the development of anemia in patients treated by regular hemodialysis (HD). Moreover, OS represents a risk factor for the development of erythropoietin (EPO) resistance in these patients. The aim of this study was to examine the role of OS regarding EPO resistance development in patients treated by regular HD. 96 patients treated with standard HD and on-line hemodiafiltration were included in this study. The patients were treated with short-acting and long-acting EPOs for anemia. The concentration of superoxide anion radical, hydrogen peroxide, thiobarbituric acid reactive substances, and nitric oxide in the form of nitrites and the activity of catalase, superoxide dismutase and reduced glutathione were measured in patients' blood spectrophotometrically. Standard biochemical analysis, inflammatory markers, nutritional status, HD parameters, and erythropoietin resistance index were also determined. Patients with resistance to short-acting EPO had significantly lower concentration of hemoglobin in the blood and hematocrit value, a significantly higher serum ferritin concentration, and significantly lower catalase activity in erythrocytes than patients without EPO resistance. Patients with resistance to long-acting EPO have a significantly lower hemoglobin concentration in the blood, hematocrit values, and serum concentration of prealbumin and vitamin D, as well as significantly higher concentration of C-reactive protein, superoxide anion, and hydrogen peroxide concentration than those without resistance. OS significantly contributes to EPO resistance development. OS, higher ferritin and CRP levels, lower hemoglobin, hematocrit and prealbumin levels, and vitamin D deficiency represent significant risk factors for EPO resistance development in HD patients.

Relation Between Oxidative Stress and Carotid Artery Atherosclerosis in Hemodyalisis Patients

INTRODUCTION Oxidative stress represents a significant risk factor for the accelerated development of atherosclerosis in a population of patients on regular hemodialysis. Oxidative stress induced by hemodialysis can be triggered with both the bioincompatibility of dialysis membrane and increased endotoxin concentration in a hemodialysis solution.

AIM The aim of this study was to investigate the correlation between the parameters of oxidative stress, microinflammation, nutrition, secondary hyperparathyroidism and carotid artery intima-media thickness in patients on regular hemodialysis.

METHODS One hundred and twenty five patients treated with standard hemodialysis and on-line hemodiafiltration with “high-flux” polysulfone dialysis membrane were examined. The following parameters of oxidative stress were measured : index of lipid peroxidation - measured as TBARS, nitric oxide in the form of nitrite - NO2-, super oxide anion radical - O2- and hydrogen peroxide - H2O2, catalase, superoxide dismutase (SOD) and reduced glutathione activity. For statistical analysis of results, the following tests were used: the Kolmogorov-Smirnov test, the Spirman test and the Pearson correlation test.

RESULTS Oxidative stress affects atherosclerosis of the carotid arteries in patients treated with regular hemodialysis and online hemodiafiltration. There is a statistically significant positive correlation between H2O2 concentration and the thickness of the carotid arteries` intima-media. High statistically significant positive correlation was found between TBARS concentration and carotid arteries intima-media thickness, while a high statistically significant negative correlation was found between SOD activity and a carotid artery intima-media thickness. There is a statistically significant negative correlation between the serum albumin and prealbumin concentration and a carotid artery intima-media thickness.

CONCLUSION Oxidative stress may be a significant risk factor for the carotid artery atherosclerosis development in patients treated with regular hemodialysis.