The authors examined in 37 patients dialyzed in a dialysis centre in Brno-Bohunice, a region with selenium deficiecy in the population the serum selenium and glutathione peroxidase level before and after 4-hour standard haemodialysis across a polysulphone membrane. In 78 % patients sele- nium deficiency was found. The mean value in the whole group was 33.4 mg Se/l. The reference range for the Brno population is 41.3 - 80.7 mg/l. After dialysis a rise of the serum selenium level by 15.4 mg/l occurred due to haemoconcentration during ultrafiltration and also due to redistribution of fluids and selenium during dialysis. In anuric patients selenium does not cumulate in serum, although it is excreted in healthy subjects mainly in the urine. Due to the closer bond with selenoproteins it is not significantly separated by dialysis. Glutathione peroxidase assessed in whole blood was in 76 % patients before dialysis within the reference range and did not change significantly as a result of dialysis. Selenium deficiecy participates significantly in the inadequate activity of antioxidant systems in the organism and in dialyzed patients it potentiates the development of chronic complications.

        Key words: Selenium - Glutathione peroxdase - Haemodialysis.