title: Levels of seminal free L(-) carnitine in fertile and infertile men.
abstract: Data about the levels of free L-carnitine, an epididymal marker in human semen, are contradictory and unclear, particularly in their relationship to fertility. This can perhaps be explained by the absence of any studies of seminal L-carnitine in a large group of fertile men, and by the lack of consideration of factors influencing its secretion. In this study, free L-carnitine was determined using a spectrophotometric method in deproteinized semen samples from fertile (n = 162) and infertile men without azoospermia (n = 303). Our results can be summarized as follows: Infertile men were found to have significantly lower (P less than 0.001) seminal carnitine levels (755 +/- SD 499 nmoles) compared with fertile men (1010 +/- 570). Percentiles have been calculated for fertile men, and 'normal' values proposed (10th percentile = 390 and 90th percentile = 1830 nmoles). Distribution of the levels of L-carnitine were asymmetric in fertile as well as in infertile men (median: 922 nmoles vs 645). In both groups, a significant increase in carnitine levels was observed with increasing length of abstinence, and a decrease in the ratio of carnitine/days of abstinence. Methodological, physiological and pathological factors which may explain these results are discussed.
mesh_terms: D002331:Carnitine / Q000378:metabolism*; D004822:Epididymis / Q000378:metabolism; D006801:Humans; D007248:Infertility, Male / Q000378:metabolism*; D008297:Male; D012016:Reference Values; D012661:Semen / Q000378:metabolism*; D012746:Sexual Abstinence; D013997:Time Factors
chemical_list: D002331:Carnitine