L-carnitine and haemodialysis: double blind study on muscle function and metabolism and peripheral nerve function

Twenty-eight haemodialysis patients were randomized to L-carnitine, 2 g i.v. three times a week, and saline over a 6-week period. No obvious deficiency of carnitine was found in vastus lateralis with a median value of 12.9 mmol/kg dry weight; range 6.2-21.4. Female patients had lower total plasma carnitine compared to female controls, p less than 0.002, whereas no decrease was found in males. No relationship was found between muscle and total plasma carnitine. After carnitine administration the muscle carnitine level increased about 60%, p less than 0.01, and the total plasma carnitine level more than tenfold, whereas the initially high degree of acylation decreased, p less than 0.02. Maximum dynamic muscular strength was reduced with a mean value of 44% compared with healthy controls. Total metabolic activity of isolated skeletal muscle fibres, measured as heat production with a new technique using a perfusion microcalorimeter, showed a median value of 0.40 mW/g, 25% lower than normal, p less than 0.02. Carnitine administration had no effect on several different tests of muscular function. Neurophysiologically, discrete improvements in the temperature responses were recorded, but no changes in sensory and motor nerve conduction velocities or in vibration thresholds were noted. No symptomatic improvement was observed even in patients with the lowest carnitine levels prior to treatment. Our data do not support the hypothesis that carnitine deficiency contributes to muscle and nerve dysfunction in patients on chronic haemodialysis.