Sperm DNA Fragmentation in Infertile Men: Associations with Semen Parameters and Thyroid Dysfunction

Abstract

Background: Male infertility accounts for nearly half of all infertility cases and is influenced by multiple biological and environmental factors. Conventional semen analysis provides limited information on sperm function. The sperm DNA fragmentation index (DFI) has emerged as a key biomarker reflecting sperm chromatin integrity and fertilizing potential. Evidence from Indian men remains scarce and inconsistent. Aim: To evaluate the association of semen quality, lifestyle habits and systemic conditions with sperm DNA fragmentation among infertile men. Study Design and Place: A retrospective cross-sectional study conducted at birthright fertility by rainbow hospitals, Hyderabad, India. Materials and Methods: Records of 326 men evaluated between January 2023 and May 2025 were reviewed. Clinical details including age, body mass index (BMI), infertility type and duration, lifestyle factors, and comorbidities were collected. Semen analysis followed WHO 2021 guidelines. Sperm DFI was assessed using the Sperm Chromatin Dispersion method (Sperm Chroma kit, Cryolab International, India). Correlation and logistic regression analyses identified predictors of poor DFI (>25%). Results: The median (IQR) DFI was 24% (19–28%), with 39% showing poor DFI. DFI correlated negatively with sperm count (ρ = –0.313, p < 0.001), motility (ρ = –0.233, p < 0.001), and morphology (ρ = –0.137, p = 0.0135), but not with age or BMI. Hypothyroidism independently predicted higher DFI, while higher sperm count was associated with lower odds of poor DFI. Conclusion: Higher DFI was associated with poorer semen parameters and systemic factors such as hypothyroidism, rather than age or lifestyle habits. Incorporating DFI and thyroid screening with routine semen analysis may improve evaluation and management of male infertility.