Background: L-Carnitine is an endogenous compound thought to be helpful in treating patients with dialysis-related hypotension and muscle cramps; however, sufficient evidence for these indications is lacking.
Study design: Systematic review and meta-analysis.
Setting & population: Adult patients with end-stage renal disease receiving long-term hemodialysis.
Selection criteria for studies: All published English-language reports of randomized placebo-controlled trials of L-carnitine supplementation in adult long-term hemodialysis patients.
Intervention: Supplemental L-carnitine (or placebo) for at least 8 weeks.
Outcome: Random-effects pooled odds ratio for intradialytic cramping or hypotension in L-carnitine-treated participants.
Results: Of 317 potentially relevant articles, 7 (total enrollment of 193 patients) met criteria for inclusion. Four articles reported results for both hypotension and cramps, 1 had results for only hypotension, and 2 reported results for only cramps. Using data from all 6 relevant trials, the pooled odds ratio for cramping after L-carnitine supplementation was 0.30 (95% confidence interval, 0.09 to 1.00; P = 0.05). Analysis of the 5 studies examining the response of intradialytic hypotension to l-carnitine supplementation yielded a pooled odds ratio of 0.28 (95% confidence interval, 0.04 to 2.23; P = 0.2).
Limitations: The small number of available studies yielded limited statistical power. In addition, there was considerable interstudy heterogeneity.
Conclusions: Although suggestive in the case of muscle cramping, the available evidence does not confirm a beneficial effect of L-carnitine supplementation on dialysis-related muscle cramping or intradialytic hypotension. Additional study in the form of large rigorous randomized trials is needed in both cases.