Association between normalized oxidation-reduction potential and conventional semen parameters: a systematic review and meta-analysis

Xiejunhao Zheng^1,2,#, Zitong Wang^1,2,#, Tiange Wu^1,2,#, Chunhui Liu¹, Ming Chen^1,*, Chao Sun^1,*
1 Department of Urology, Zhongda Hospital, Southeast University, Nanjing, China
2 Department of Urology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
* Corresponding Author: Ming Chen. Email: email ; Chao Sun. Email: email
# These authors contribute equally to this study and are listed as co-first authors

Canadian Journal of Urology https://doi.org/10.32604/cju.2026.083360

Received 02 April 2026; Accepted 08 June 2026; Published online 03 August 2026

Abstract

Objectives: Reactive oxygen species (ROS) are key contributors to male infertility, yet conventional assessments often evaluate oxidative stress in isolation without considering the reductive counterpart. Normalized oxidation-reduction potential (nORP), commonly measured using the MiOXSYS system, has been proposed as a marker of seminal redox status. This systematic review and meta-analysis aimed to evaluate the associations between nORP and conventional semen parameters and sperm DNA fragmentation (SDF). Methods: A systematic review and meta-analysis were conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Random-effects models were used to pool correlation coefficients between nORP and semen parameters. PubMed, Web of Science, and Embase were searched from database inception to 24 September 2024. Eligible studies reporting correlations between nORP and semen parameters or SDF were included. Correlation coefficients were pooled after Fisher’s Z transformation. Heterogeneity was assessed using I², and study quality was evaluated using a modified Newcastle-Ottawa Scale. Results: Random-effects meta-analyses showed that higher nORP was significantly associated with lower total sperm count (r = −0.76, n = 9525, 95%CI: −0.84, −0.64), total motility (r = −0.35, n = 9099, 95%CI: −0.44, −0.25), progressive motility (r = −0.40, n = 8236, 95% CI: −0.49, −0.30), normal sperm morphology (r = −0.42, n = 5206, 95%CI: −0.52, −0.31) and positive correlation between nORP and SDF (r = 0.25, n = 9015, 95%CI: 0.11, 0.40). Substantial heterogeneity was observed across most pooled analyses. Conclusion: Normalized ORP is associated with several semen quality parameters and SDF, suggesting that it may serve as a complementary marker of oxidative-stress-related semen impairment. Given that sperm concentration is incorporated into the calculation of nORP, future prospective studies reporting nORP are warranted to clarify its incremental diagnostic and prognostic value beyond routine semen analysis. Registration: Prospero (CRD42024608468).