OBJECTIVETo evaluate the difference of the free L-carnitine level in seminal plasma between fertile and infertile men and the correlation of free L-carnitine with semen quality, and to study the effect of L-carnitine on male fertility and its role in the evaluation and treatment of male infertility.

METHODSSemen samples of 230 infertile (normozoospermia, n=117, oligozoospermia, n=81, azoospermia, n=32) and 30 fertile men were collected and the level of free L-carnitine in seminal plasma and such sperm parameters as sperm concentration, motility and vitality, were determined by high performance liquid chromatography and computer-assisted semen analysis system, respectively. The results were analyzed with the SPSS 12.0 software.

RESULTSThe level of free L-carnitine in the seminal plasma of the fertile men was significantly higher than that of the infertile (P < 0.01). The lower the sperm concentration, the weaker the sperm vitality, the more significant the difference. The level of free L-carnitine in the semen was positively correlated with sperm concentration (r = 0.521, P < 0.001), and sperm motility (r = 0.319, P < 0.001) and vitality (r = 0.251, P < 0.001).

CONCLUSIONThe level of free L-carnitine in seminal plasma, significantly correlated with sperm concentration, motility and vitality, can be taken as a biochemical index used as a guidance for the clinical treatment of male infertility as well as for the study on the mechanisms of male reproduction.