RETINOL AND ALPHA-TOCOPHEROL IN HEMODIALYSIS-PATIENTS

The biological effects of reactive oxygen species and other radicals c ontrolled by antioxidant mechanisms are modified by various enzymes an d other substrates. Antioxidant substrates are divided into those with lipophilic and hydrophilic groups. Retinol and tocopherol are the mai n representations of lipophilic antioxidants. The aim of the present s tudy was to describe the changes of retinol and alpha-focopherol which occurred in hemodialysis (HD) patients in respect to the influence of antioxidant systems. The experimental group consisted of 14 patients on regular HD treatment The control group consisted of 14 healthy bloo d donors. HPLC was used to measure retinol and alpha-tocopherol in ser um. We found that the retinol concentration was significantly higher i n HD patients compared to controls (2.35 +/- 0.95 versus 0.90 +/- 0.23 mg/L, p < 0.0001). The concentration of alpha-tocopherol in serum was not different in both study groups (7.32 +/- 3.01 versus. 8.94 +/- 3. 57 mg/L). A review of the MEDLINE database since 1985 found a few refe rences concerning these important antioxidant vitamins in HD patients and these contained contrasting results. It has been suggested that so me of the complications related to HD including cardiovascular complic ations, anemia and atherosclerosis may be due to ineffective antioxida nt systems and/or to increased free oxygen radical production. The que stion about supplementation of antioxidants in HD patients is open alt hough there are some positive data regarding the use of moderate and s afe selenium supplementation in HD patients. HD patients treated by er ythyopoietin had increased plasma concentration of retinol and normal level of alpha-tocopherol compared to healthy group. However this posi tive finding did not affect lipid peroxidation, which is increased in HD patients and leads to some complications during HD treatment.