Objective: The deficit of L-carnitine was repeatedly proved in a chronic haemodialysis (HD) program. This deficit leads to a disorder of energy metabolism and can cause some complications. The aim of our study is to compare serum concentrations of free carnitine in HD patients (before and after HD) and healthy population and evaluate their changes in consequence of supplementation. Material and Method: We observed 85 HD patients in a regular dialysis program. At the beginning of this study the levels of carnitine were measured and compared with the healthy control group. The group of HD patients was divided into two comparable subgroups. The first one (46 patients) was supplemented by L-carnitine (15 mg/kg i. v. after each HD), the other one (39 patients) took placebo. The laboratory examination was performed before the study, after 3 and 6 months of supplementation. The level of carnitine was always determined before and after each HD. Free carnitine in serum was detected by enzymatic photometric test from Roche on the Olympus AU 400 analyzer. The results were evaluated by unpaired t-test and by other statistical calculations in Microsoft Excel program. Results: The average carnitine concentration in healthy persons was 40.1± 8.9 µmol/l; 43.4 ± 8.1 µmol/l in men and 33.1 ± 5.6 µmol/1 in women. In HD patients carnitine concentrations were 30.5 ± 10.3 µmol/l before HD (P < 0.001 for the difference between controls and patients before HD; CI = 6.5–12.7) and 9.4 ± 4.6 µmol/l after it (P < 0.001 vs. predialysis values). No significant differences were shown between men and women. Both subgroups of HD patients had comparable levels of L-carnitine in serum at the beginning of the study. While this value markedly increased in supplemented patients after 3 and 6 months of supplementation (29.5 ± 8.7 µmol/l vs. 135.3 ± 39.9 µmol/l vs. 111.7 ± 35.7 µmol/l; P < 0.001), there was a tendency to a gentle decrease in non-supplemented subgroup (30.4 ± 11.5 µmol/l vs. 30.2 ± 12.5 µmol/l vs. 25.7 ± 10.0 µmol/l). The levels of L-carnitine were still higher when the supplementation had ended (the concentration 2 months after the end of supplementation was 65 ± 16.6 µmol/l; P < 0.01 vs. initial values).Conclusion: About 60% of the patients before HD had a significant deficit of free L-carnitine in serum. The others had comparable values with the healthy population. All observed patients had lower values of L-carnitine after HD (approximately 30% of the value before HD). While this value slightly decreased in the non-supplemented patients, there was a high increase after carnitine supplementation, so that the values after HD were within reference ranges for healthy polupation. These higher levels still remained two months after the end of supplementation. As carnitine is necessary for the energy metabolism, its deficit can lead to serious complications of haemodialysis treatment. Therefore it is necessary to consider its supplementation in HD patients where the deficit had been verified.

        Key words: L-carnitine, haemodialysis, energy metabolism, deficit, supplementation.