Seminal biomarkers and their correlations to semen parameters in subfertile men

Research question: To assess the levels of seminal biomarkers fructose, zinc and citrate and their correlations to semen parameters in infertile men.

Design: 200 infertile male participants undergoing fertility assessment at Singapore General Hospital (SGH), Singapore were recruited prospectively, from June 2020 to August 2021. Their semen samples were assessed for seminal parameters, biomarker levels of fructose, citrate and zinc, leukocyte concentrations and aerobic cultures. They were also assessed for their smoking habits.

Results: Sperm concentrations were negatively correlated to seminal fructose levels, r = -0.262, P < 0.001. Progressive motility were positively correlated to seminal citrate levels, r = 0.181, P = 0.014. Sperm morphology and total motile sperm count (TMSC) were positively correlated to seminal zinc and citrate levels, P < 0.05. Zinc and citrate levels were significantly reduced in teratozoospermia, asthenoteratozoospermia and oligoasthenoteratozoospermia groups compared to normozoospermia, P < 0.05. The presence of infection was associated with elevated leukocyte concentrations, lower sperm concentration (12.5 vs 55.8 million/mL, P = 0.024) and fructose levels (35.5 vs 49.2 µmol/ejaculate). Heavy smokers compared to light smokers, had lower sperm concentrations (35.3 vs 49.4 million/mL), TMSC (30.9 vs 47.5 million) and zinc levels (4.9 vs 6.7 µmol/ejaculate) and significantly lower citrate levels (52.6 vs 79.2 µmol/ejaculate, P = 0.029).

Conclusions: Higher zinc and citrate levels correlated with better progressive motility, sperm morphology and TMSC. Smoking negatively impacted zinc and citrate levels, thereby affecting sperm quality. In conclusion, the inclusion of biomarkers in basic male work-up assessment would assist in identifying common deficiencies and aid in adequate replacement therapy.