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, particuliarly in their releationship 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 < 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. Copyright © 1984, Wiley Blackwell. All rights reserved