Carnitine metabolism in uremia

Carnitine is a conditionally essential metabolite that plays a critical rol e in cell physiology by participating in transesterification reactions and preventing organic acid accumulation. A number of disease states are charac terized by carnitine depletion that may lead to metabolic and clinical dist urbances. In maintenance hemodialysis, carnitine is lost through dialytic m embranes, leading in selected patients to carnitine depletion with a relati ve increase of the esterified forms. Carnitine supplementation after or dur ing dialysis counteracts such alterations and may be associated with some c linical benefits. Recent meta-analyses of the literature indicate that carn itine supplementation in hemodialysis patients may improve the hematologica l status (allowing a reduction of the requirement for erythropoletin), the exercise tolerance, the plasma lipid profile, and the intradialytic symptom s. In addition, carnitine supplementation may improve cardiac functions, pr otein metabolism, and insulin resistance. Carnitine supplementation has bee n recently approved by the US Food and Drug Administration not only for the treatment, but also for the prevention of carnitine depletion In dialysis patients. Furthermore, clinical guidelines developed by both American and E uropean nephrological societies suggest that a trial with carnitine supplem entation could be recommended in selected dialysis patients who do not adeq uately respond to standard therapy for certain conditions, such as severe a nd persistent muscle cramps or hypotension during dialysis, lack of energy affecting quality of life, skeletal muscle weakness or myopathy, cardiomyop athy, and anemia of uremia unresponsive to or requiring large doses of eryt hropoietin. (C) 2001 by the National Kidney Foundation, Inc.