Evaluation of the effect of intravenous L-carnitine therapy on function, structure and fatty acid metabolism of skeletal muscle in patients receiving chronic hemodialysis.

Chronic hemodialysis (HD) leads to significant losses of carnitine from plasma and muscle. Because L-carnitine is important in the production of energy from fatty acid oxidation (FAO) in muscle, we examined the role of carnitine replacement by administering therapeutic doses of intravenous carnitine to 14 male patients receiving HD. Placebo or carnitine was given 2 g i.v. 3 times weekly for 6 months in a double-blind manner. To evaluate long-term toxicity of carnitine, all patients subsequently received 1 g i.v. carnitine for 10 months. Patients were rated for muscle strength each week. After 6 months, definite improvement in strength occurred in 4 of 7 carnitine-treated patients and in none of 7 controls. During the subsequent 10 months of carnitine administration, no adverse effects were noted and muscle strength improved in 9 of 14 patients. Muscle biopsy was performed in 13 patients before and after the first 6 months of treatment and in 6 healthy controls. FAO and carnitine were measured in each muscle biopsy. FAO was significantly lower in both carnitine- and placebo-treated HD patients compared to healthy controls. Although carnitine therapy increased the muscle concentration of carnitine 3-fold in muscle of HD patients, muscle FAO did not increase significantly and never reached the level of healthy controls. Muscle histopathology and ultrastructure were not specific for HD myopathy. Carnitine may be useful in treating some patients with muscle weakness related to HD.