Design: A systematic review and meta-analysis, Level II.

Setting: National Referral Center, Department of Operative Gynecology

Patients or Participants: Women with and without endometriosis.

Interventions: PubMed, The Cochrane Library, ClinicalTrials.gov, Scopus, Embase, and Google Scholar. The search was performed on studies published before November 1, 2023, to identify articles evaluating the concentrations of iron metabolism markers in the peritoneal fluid. Registration number: CRD42023457624.

Measurements and Main Results: The initial search produced 429 articles. 16 studies were included for qualitative analysis. Based on ROBINS-I tool, trials had low or moderate risks of bias. The primary analysis aimed to compare iron levels between the endometriosis and control groups. This comparison included 3 studies involving 154 patients (MD = 16.78, 95% CI: 3.40–30.15, P = 0.01, I²=0%). According to this meta- analysis, iron concentrations in PF were statistically significant higher in the endometriosis group. Comparison of lactoferrin levels between endometriosis and control groups included 3 studies evaluating 217 patients (MD = 0.24, 95% CI: -0.13 to 0.61, P = 0.20, I²=0%). Based on this meta-analysis, lactoferrin levels in PF were not statistically different between groups. As for ferritin level, it was evaluated in 3 studies assessing 164 patients with statistically significant difference in endometriosis group compared controls (MD = 1.21, 95% CI: 0.34–2.09, P = 0.007, I²=60%)

Conclusion: We determined that patients with endometriosis tend to have increased levels of such iron metabolism markers as ferritin and iron in the PF. Therefore, levels of these markers may be used in the future as a diagnostic tool. Understanding these roles of iron and iron metabolism markers in the pathogenesis of endometriosis could potentially lead to more effective treatment and early diagnostics of the disease.