Objective: To evaluate the effect and safety of L-carnitine in the treatment of idiopathic oligoasthenozoospermia based on current clinical evidence.
Methods: We searched the Cochrane Library, PubMed, MEDLINE, EMBASE, CNKI, VIP, CBM and Wanfang Database from the establishment to April 2014 for the published literature on the treatment of idiopathic oligoasthenozoospermia with L-carnitine. We conducted literature screening, data extraction, and assessment of the methodological quality of the included trials according to the inclusion and exclusion criteria, followed by statistical analysis with the RevMan 5. 2 software.
Results: Seven randomized controlled trials involving 751 patients with idiopathic oligoasthenozoospermia met the inclusion criteria, and 678 of them were included in the meta-analysis. L-carnitine treatment achieved a significantly increased rate of spontaneous pregnancy as compared with the control group (RR = 3.2, 95% CI 1.74 to 5.87, P = 0.0002). After 12-16 and 24-26 weeks of medication, total sperm motility (WMD = 5.21, 95% CI 2.78 to 7.64, P < 0.0001 and WMD = 9.29, 95% CI 1.28 to 17.29, P = 0.02) and the percentage of progressively motile sperm (WMD = 12.44, 95% CI 4.58 to 20.31, P = 0.002 and WMD = 9.76, 95% CI 3.56 to 15.97, P = 0.002) were remarkably higher than those in the control group, but no statistically significant differences were observed in sperm concentration between the two groups (WMD = 4.91, 95% CI -2.63 to 12.45, P = 0.2 and WMD = 0.93, 95% CI -3.48 to 5.34, P = 0.68). After 12-16 weeks of treatment, the percentage of morphologically abnormal sperm was markedly decreased in the L-carnitine group as compared with the control (WMD = -2.48, 95% CI -4.35 to -0.61, P = 0.009), but showed no significant difference from the latter group after 24-26 weeks (WMD = -4.38, 95% CI -9.66 to 0.89, P = 0.1). No statistically significant difference was found in the semen volume between the two groups after 12-16 or 24-26 weeks of medication (WMD = -0.13, 95% CI -0.43 to 0.18, P = 0.42 and WMD = 0.28, 95% CI -0.02 to 0.58, P = 0.07). No serious L-carnitine-related adverse events were reported in 4 of the randomniized controlled trials.
Conclusion: The current evidence indicates that L-carnitine can improve spontaneous pregnancy and semen parameters in the treatment of idiopathic oligoasthenozoospermia, with no serious adverse reactions.