Association Between Zinc Ion Concentrations in Seminal Plasma and Sperm Quality: A Chinese Cross-Sectional Study

This study investigates the impacts of zinc ion concentration in in seminal plasma and the total amount of Zn²⁺ per ejaculation on sperm quality evaluation parameters. In addition, we assessed the reliability of using zinc content in seminal plasma to evaluate sperm quality. We analyzed semen from 964 men and found that men over 40 years old had significantly lower concentrations of Zn²⁺ in ejaculated semen compared to other age groups (p < 0.05), with no significant difference in Zn²⁺ concentrations among other age groups (p > 0.05). The total amount of Zn²⁺ in one ejaculation did not show a statistical difference between the normal semen and the abnormal semen groups (p > 0.05). Statistical differences were observed in sperm kinetic parameters and DNA fragmentation index between the normal Zn²⁺ total amount group and the abnormal group (p < 0.05). However, there was no statistical difference in morphological parameters (p > 0.05). Spearman correlation analysis showed a negative correlation between Zn²⁺ concentrations in seminal plasma, age, and sperm fructose and a positive correlation between semen volume, abstinence time, sperm concentration, neutral α-glycosidase, and citric acid content (p < 0.05). The receiver operating characteristic curve analysis demonstrated that Zn²⁺ concentrations had poor accuracy and specificity in assessing sperm quality (p > 0.05). Although there is a partial correlation between Zn²⁺ concentrations in seminal plasma and certain semen quality parameters, relying solely on Zn²⁺ concentrations to evaluate sperm quality lacks accuracy and specificity.