L-Carnitine supplementation for adults with end-stage kidney disease requiring maintenance hemodialysis: a systematic review and meta-analysis.

Background: A previous meta-analysis indicated that L-carnitine significantly increased hemoglobin and decreased the required erythropoietin dose in maintenance hemodialysis patients. Objective: An updated systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to reevaluate effects of L-carnitine. Design: The Cochrane Library, PubMed, and EMBASE databases (31 December 2012) were searched to identify RCTs that investigated effects of L-carnitine in adults with end-stage kidney disease that required maintenance hemodialysis. Results: Forty-nine RCTs (1734 participants) were included. L-Carnitine significantly decreased serum low-density lipoprotein (LDL) (mean difference: -5.82 mg/dL; 95% CI: -11.61, -0.04 mg/dL) and C-reactive protein (CRP) (-3.65 mg/L; -6.19, -1.12 mg/L). There were no significant differences in triglycerides (-0.89 mg/dL; -29.32, 27.53 mg/dL), cholesterol (0.14 mg/dL; -6.15, 6.42 mg/dL), high-density lipoprotein (1.13 mg/dL; -2.44, 4.70 mg/dL), hemoglobin (0.68 g/dL; 0.14, 1.50 g/dL), hematocrit (2.04%; -1.39, 5.48%), albumin (1.65 g/L; -0.22, 3.51 g/L), or the required erythropoietin dose (-0.76 KU/wk; -1.75, 0.23 KU/wk). No adverse effects were reported. Conclusions: This meta-analysis failed to confirm the previous findings regarding the effects of L-carnitine on hemoglobin and the erythropoietin dose but showed that L-carnitine significantly decreased serum LDL and CRP. The extent of the decrease in LDL was not clinically relevant, whereas the significant decrease in CRP was both statistically and clinically relevant. However, the relevance of decrease in CRP with hard endpoints such as all-cause mortality and cardiovascular complications still remains to be clarified.