The majority of haemodialysis patients are treated with intravenous iron preparations. Some authors use concurrent administration of vitamin C in patients with high ferritin levels assuming that it improves iron mobilization from its stores. An excessive iron load can cause hydroxyl radical formation (Fenton´s reaction). Ascorbic acid has two contrary effects: it is a potent antioxidant, on the other hand, it can reduce Fe(III) to Fe(II) compounds and promote Fenton´s reaction. The aim of the study was to study the effect of intravenous iron administration in haemodialysis patients on oxidative stress parameters and the influence of concurrent vitamin C administration on these parameters. 16 patients were treated with iron (in the form of ferric saccharate) in intravenous infusion during last 30 min of haemodialysis. During the subsequent week, the same patients were dialyzed without iron administration. The same pattern was applied with continuous i.v. administration of ascorbic acid (500 mg) during the whole haemodialysis. Iron concentration, transferrin saturation, plasma malondialdehyde and intraerythrocyte glutathione were measured before iron administration and immediately after it (and in a control group without iron). Intravenous administration of iron led to high iron concentrations and the average transferrin saturation exceeded 165 %. At the same time, malondialdehyde increased significantly while the glutathione concentration remained constant. There was a strong positive correlation between malondialdehyde concentration and plasma iron or transferrin saturation.We can conclude that intravenous iron increases oxidative stress in haemodialysis patients. Ascorbic acid administration did not have an antioxidative or prooxidative effects.

        Key words: oxidative stress, malondialdehyde, iron, ascorbic acid, haemodialysis.