Effects of Carnitine on Nutritional Parameters in Patients with Chronic Kidney Disease: An Updated Systematic Review and Meta-Analysis

Protein energy malnutrition is a common problem in patients with chronic kidney disease (CKD). Scattered reports indicate that supplementation of Carnitine may improve patients’ clinical symptoms, with significant improvement in nutritional parameters. This systematic review was done to document the evidences of Carnitine effects in nutritional status of CKD patients. Peer-reviewed RCTs on Carnitine administration at any dose in CKD patients with at least four weeks of follow-up were including in the meta-analysis. Online databases (PubMed/Medline, ISI Web of Science, Embase, and Scopus) were searched to October 2017 using selected MeSH terms related to the study topic. Data was extracted independently by two reviewers using a standard form and then cross-checked. Statistical analyses were carried out with Comprehensive Meta-analysis software. Data are presented as standard mean difference (SMD) and 95% confidence interval (CI). According to the predefined criteria, a total of 14 randomized controlled clinical trials were included and screened for data extraction by two reviewers, separately. The preliminary results extracted from meta-analysis have shown that Carnitine can significantly increase the levels of albumin (SMD: -0.861; 95% CI: -1.321, -0.402), total protein (SMD: -0.418; 95% CI: -0.695, -0.141), total cholesterol (SMD: -0.350; 95% CI: -0.564, -0.135), LDL cholesterol (SMD: -0.362; 95% CI: -0.551, -0.173), transferrin (SMD: -1.465; 95% CI: -1.822, -1.108), and hemoglobin (SMD: -0.525; 95% CI: -0.732, -0.318); however there were no conclusive effects of Carnitine on body weight (SMD: -0.057; 95% CI: -0.404, 0.291) and BMI (SMD: -0.567; 95% CI: -1.548, 0.415), in pooled analyses. The results of this meta-analysis showed that there are considerable useful pieces of evidence so far about the effect of Carnitine on nutritional factors; however, there is still doubt about some evidences with this regard. It seems necessary to carry out clinical trials with stronger designs to evaluate the impact of these primary outcomes on the patients' clinical conditions. Having this evidences, the potential role of Carnitine in improving malnutrition consequences in CKD patients would be clearly defined.