Integrating Thyroid Autoantibodies With CA125 Enhances Diagnostic Precision for Ovarian Endometriosis: A Retrospective Study of 885 Patients

Aim This study aimed to compare clinical characteristics and evaluate diagnostic biomarkers in ovarian endometriosis, with a focus on thyroid autoimmunity associations. Methods A retrospective analysis of 885 patients (441 ovarian endometriosis cases; 444 benign ovarian tumor controls) was conducted. Clinical parameters, thyroid function markers (FT3, FT4, TSH), thyroid autoantibodies (TPOAb, TGAb), and CA125 levels were analyzed. Multivariate regression and ROC curves assessed diagnostic utility. Results Ovarian endometriosis patients exhibited higher dysmenorrhea prevalence (49.7% vs. 15.3%, p < 0.001), bilateral cysts (26.1% vs. 8.8%, p < 0.001), endometrial polyps (21.9% vs. 15.9%, p = 0.015), and uterine fibroids (35.6% vs. 26.2%, p = 0.003) versus controls. Elevated CA125 (75.3% vs. 10.8%), TPOAb (56.9% vs. 6.5%), and TGAb (68.5% vs. 12.4%) incidences were observed in endometriosis ( p < 0.001). Autoimmune thyroid disease co‐occurrence was significantly higher in cases (51% vs. 15%, p < 0.001). Multivariate analysis identified CA125 (OR = 18.4, 95% CI: 12.5–27.6), TPOAb (OR = 2.63, 95% CI: 1.46–4.77), and TGAb (OR = 4.03, 95% CI: 2.48–6.60) as independent risk factors ( p ≤ 0.001). ROC analysis revealed AUCs of 0.895 (CA125), 0.793 (TGAb), and 0.736 (TPOAb); their combination achieved superior diagnostic accuracy (AUC = 0.924, sensitivity 88.9%, specificity 84.5%). Conclusion This large‐scale retrospective analysis demonstrates that the integration of serum CA125 with thyroid autoantibodies (TPOAb/TGAb) generates a synergistic diagnostic signature for ovarian endometriosis, achieving unprecedented discriminative accuracy (AUC 0.924) that significantly surpasses individual biomarker testing. The > 3‐fold elevated co‐occurrence of autoimmune thyroid dysfunction in cases reinforces an underrecognized immune‐endocrine interplay in disease pathogenesis. These findings support incorporating thyroid autoimmunity screening into standard diagnostic workups to optimize risk stratification and personalized management pathways for symptomatic patients.