Impact of haemodialysis on individual endogenous plasma acylcarnitine concentrations in end-stage renal disease

Background: Patients with end-stage renal disease (ESRD) undergoing long-term haemodialysis exhibit low L-carnitine and elevated acylcarnitine concentrations. This study evaluated endogenous concentrations of an array of acylcarnitines (carbon chain length up to 18) in healthy individuals and ESRD patients receiving haemodialysis, and examined the impact of a single haemodialysis session on acylcarnitine concentrations.

Methods: Blood samples were collected from 60 healthy subjects and 50 ESRD patients undergoing haemodialysis (pre- and post-dialysis samples). Plasma samples were analysed for individual acylcarnitine concentrations by electrospray MS/MS.

Results: Of the 31 acylcarnitines, 29 were significantly (P<0.05) elevated in ESRD patients compared with healthy controls; in particular, C5 and C8:1 concentrations were substantially elevated. For acylcarnitines with a carbon chain length less than eight, plasma acylcarnitine concentrations decreased significantly over the course of a single dialysis session; however, post-dialysis concentrations invariably remained significantly higher than those in healthy subjects. Dialytic removal of acylcarnitines diminished once the acyl chain length exceeded eight carbons.

Conclusions: The accumulation of acylcarnitines during long-term haemodialysis suggests that removal by haemodialysis is less efficient than removal from the body by the healthy kidney. Removal is significantly correlated to acyl chain length, most likely due to the increased molecular weight and lipophilicity that accompanies increased chain length.