Objective: Deficit of carnitine in hemodialysis (HD) patients can promote oxidative stress due to impairment of lipid metabolism. Supplementation with carnitine could improve beta-oxidation of fatty acids, so decrease triglycerides and also malondialdehyde which is a marker of lipid peroxidation. Material and Methods: We studied 91 HD patients divided into two comparable groups. The first one (N = 50) was supplemented by L-carnitine for 6 months (15 mg/kg i. v. after each dialysis session, i. e. three times weekly), the other one (N = 41) took placebo. Changes in pre-dialysis serum free carnitine, triglycerides and malondialdehyde (as thiobarbituric acid reactive substances) during supplementation were monitored. Our results were statisticaly evaluated by Wilcoxon’s paired test. Results: Serum carnitine concentration increased significantly in the supplemented group from 30.20 ± 9.02 to 112.30 ± 35.33 µmol/l (P < 0.0001). In the placebo group it decreased from 30.64 ± 11.83 to 25.83 ± 10.32 µmol/l (P < 0.001). Triglyceride concentration did not change significantly in the two groups. Malondialdehyde concentration decreased significantly in the supplemented group from 2.28 ± 0.65 to 2.11 ± 0.97 µmol/l (P < 0.05) and only non- -significantly in the placebo group, from 2.19 ± 0.50 to 2.14 ± 0.50 µmol/l. Conclusion: Supplementation with carnitine increased its serum concentration so that in all cases it exceeded the lower reference limit for healthy population. A significant decrease of malondialdehyde in the supplemented group reflects an improvement of fatty acid metabolism and reduction of lipid peroxidation.

        Key words: carnitine, hemodialysis, oxidative stress, fatty acids, lipid peroxidation.