Investigating the correlation between seminal testosterone and cortisol and semen parameters in normozoospermic and teratozoospermic men

Summary. Male infertility is a growing global concern, affecting even men at their reproductive peak who experience difficulties in achieving conception. Notably, even men classified as normozoospermic according to WHO criteria often face (in/sub)fertility. Hormones such as testosterone and the stress-related cortisol are believed to influence male reproductive function, although their specific roles in semen quality remain incompletely understood. This study aimed to assess testosterone and cortisol concentrations in seminal plasma and investigate their associations with semen quality in normozoospermic (N) and teratozoospermic (T) men. Semen samples were collected from 32 participants (14 N, 18 T) who were eligible for the national assisted reproduction program. Standard semen parameters were analyzed, including sperm count, motility, morphology, viscosity, and the presence of gelatinous material. Hormone levels were measured in the seminal plasma. Group comparisons were performed using the Mann–Whitney test, and associations between variables were evaluated using Spearman’s correlation and linear regression analysis. There were no significant differences in seminal plasma testosterone (p = 0.19) or cortisol (p = 0.53) levels between the N and T groups. In addition, significant differences were observed in sperm count and morphology (p < 0.0001) between the groups. In the N group, seminal cortisol levels positively correlated with sperm motility (rs = 0.76), while testosterone levels predicted both sperm motility (R² = 0.2755, p = 0.0305) and viscosity (R² = 0.6069, p = 0.0002). Additionally, a moderate negative correlation was observed between sperm count and gelatinous material in the N group (rs = -0.56). In the T group, notable correlations included testosterone–cortisol (rs = 0.87), morphology–viscosity (rs = 0.62), and a negative correlation between gelatinous material and morphology (rs = -0.50). No significant predictive models were identified in this group. In summary, testosterone and cortisol levels in seminal plasma are important markers of men's reproductive health. Although preliminary due to the limited sample size, these findings suggest a potential modulatory role for seminal testosterone and cortisol in sperm function in men with otherwise normal sperm profiles.