Low-molecular weight compounds in human seminal plasma as potential biomarkers of male infertility.

Study Question: Is the determination of antioxidants, oxidative/nitrosative stress-related compounds, purines, pyrimidines and energy-related metabolites in human seminal plasma of utility to evidence biomarkers related to male infertility?

Summary Answer: The determination of 26 metabolites in seminal plasma allowed to evidence that 21/26 of them are biomarkers of male infertility, as well as to calculate a cumulative index, named Biomarker Score, that fully discriminates fertile controls from infertile patients and partially differentiates infertile without from infertile with spermiogram anomalies.

What Is Known Already: Epidemiological studies indicated that a male factor is involved in ~50% of cases of pregnancy failure, with a significant percentage of infertile males having no alterations in the spermiogram. Further laboratory analyses of male infertility are mainly dedicated only to gross evaluations of oxidative stress or total antioxidant capacity.

Head birefringence properties are associated with acrosome reaction, sperm motility and morphology.

Birefringence in sperm heads reflects an organized and very compacted texture, indicating nuclear and acrosomal structural normality. This study performed a direct analysis of the acrosome integrity in single spermatozoa to verify whether a pattern of total or partial head birefringence reflected the acrosome status. The morphology in fresh samples was assessed according to World Health Organization criteria while the characteristics of birefringence were evaluated by polarized light.