l-Carnitine status in end-stage renal disease patients on automated peritoneal dialysis

Carnitine metabolism in patients on peritoneal dialysis (PD), particularly automated PD (APD), has not been extensively evaluated. Here, we examined levels of a large number of carnitine species in plasma from adult uremic patients treated with continuous ambulatory PD (CAPD) or APD, vetting whether l-carnitine may be used in the solution bag for APD therapy. Plasma levels of carnitine and its esters were measured by high-performance liquid chromatography/tandem quadrupole mass spectrometry in 14 patients on CAPD (3 x 1.5 % glucose daily and icodextrin overnight), 16 patients on APD (tidal modality), and 8 age- and gender-matched healthy controls. PD groups did not differ with regard to demographic characteristics, renal function, dialysis features, peritoneal function, or biochemistry. In five APD patients, we also examined the safety and efficacy of l-carnitine (5 g) addition to one night-dwell solution bag over five consecutive days. Several abnormalities were found in plasma carnitine species of PD patients as compared to controls, mainly represented by a reduction of free carnitine and an increase in acetyl-carnitine, dicarboxylic and other carnitines. The main carnitine species (free carnitine, acetyl-carnitine) were significantly lower in plasma from APD than CAPD patients. APD patients tolerated l-carnitine supplementation well, laboratory, physical and dialysis parameters proving stable. Plasma carnitine metabolism is abnormal in patients on PD, and may be influenced by the PD modality. Given the good tolerability and potential advantages of carnitine used in the PD fluid, l-carnitine-containing solution bags in APD treatment definitely merit further evaluation.