Association of leukocyte elastase in semen and seminal plasma with sperm parameters and pregnancy outcomes in male fertility.

Background: Semen analysis is the standard test for evaluating male fertility. However, it may not address all aspects of male infertility. This review explores the role of leukocyte elastase (LE) as a possible biomarker for male fertility by evaluating 28 corresponding studies.

Objectives: We aimed to explore how LE levels in semen relate to sperm quality and pregnancy outcomes.

Methods: This systematic review followed PRISMA guidelines and included studies from PubMed, Medline, Embase and Scopus (March 22-25, 2024) using the keywords 'elastase', 'sperm' and 'semen'. Out of 897 identified articles, 334 were screened, leading to 90 full-text reviews. We included 28 studies reporting sperm parameters linked to LE and excluded non-English articles, reviews and animal studies. Data collected included study details, methods, population, LE levels, sperm characteristics and pregnancy outcomes. A narrative synthesis was used because of differing study designs. Quality assessment, using the National Heart, Lung, and Blood Institute tool, rated 21 studies medium quality, 6 high and 1 low.

Results: Only a limited number of studies reported a correlation between LE levels and sperm parameters, with no significant link to sperm concentration. Overall, we did not identify a strong association between LE levels and pregnancy or fertilization rates.

Conclusions: Although LE serves as a marker for seminal leukocyte concentration, its link to sperm quality and fertility outcomes remains weak and inconsistent. Based on current evidence, LE does not appear to be a reliable diagnostic marker for male infertility. Future studies should focus on standardizing LE measurement techniques and exploring its interaction with other semen parameters to clarify its role in male fertility.