Effect of l-carnitine supplementation on renal anemia in patients on hemodialysis: a meta-analysis

Background l-carnitine is an amino acid derivative that is thought to be helpful for treating renal anemia in hemodialysis patients. However, the mechanism remains to be fully elucidated. Methods A literature search was performed on PubMed, Embase, and Cochrane Central Register of Controlled Trials to identify randomized controlled trials (RCTs) and conduct a meta-analysis for investigating the effect of l-carnitine in the treatment of renal anemia in participants receiving hemodialysis. Results A total of 18 eligible trials with 1090 participants were included in this study. l-carnitine can significantly increase plasma free l-carnitine levels (mean difference [MD]: 140.53, 95% confidence interval [CI] 102.22-178.85; P < 0.00001), decrease the erythropoietin responsiveness index (ERI; MD: -2.72, 95% CI -3.20 to -2.24; P < 0.00001) and the required erythropoiesis-stimulating agent (ESA) doses (MD: -1.70, 95% CI -2.04 to -1.36; P < 0.00001). However, the use of l-carnitine was not associated with a higher hemoglobin level (MD: 0.18, 95% CI -0.20 to 0.55; P = 0.35) and hematocrit level (MD: 1.07, 95% CI -0.73 to 2.87; P = 0.24). In subgroup analyses, the effects of l-carnitine supplementation on renal anemia in patients on hemodialysis were independent of the treatment duration and intervention routes. Conclusion The present meta-analysis indicated that l-carnitine therapy significantly increased plasma l-carnitine concentrations, improved the response to ESA, decreased the required ESA doses in patients receiving hemodialysis, and maintained hemoglobin and hematocrit levels. l-carnitine supplementation should be supported in hemodialysis patients. However, the relationship between l-carnitine treatment and long-term outcomes is still unclear. Further high-quality RCTs are needed to verify our findings.