Background: Evidence on the link between iron metabolism markers and endometriosis is limited. We aimed to investigate the associations of iron metabolism markers, including serum ferritin level and transferrin saturation, with endometriosis.
Methods: This study involved 6551 participants from the National Health and Nutrition Examination Survey (NHANES). Univariable and multivariable logistic regression analyses were used to examine the linear relationships between iron metabolism markers and endometriosis. Furthermore, restricted cubic splines were used to identify the non-linear dose-response associations.
Results: Univariable analysis showed that the factors associated with endometriosis included age, race, education level, and smoking status. In multivariable model, compared with lowest quartile, highest quartile of serum ferritin level was positively associated with endometriosis (OR: 2.11, 95% confidence intervals [CI]: 1.31, 3.40, P = 0.004), and third quartile of transferrin saturation positively associated with endometriosis (OR: 1.55, 95% CI: 1.05, 2.29, P = 0.033). The restricted cubic splines showed the non-linear (inverted U-shape) associations between serum ferritin level and transferrin saturation and endometriosis (all P for non-linear＜0.01), indicating that the ORs of endometriosis increased with serum ferritin level and transferrin saturation up to the turning point and thereafter the ORs of endometriosis did not significantly increase with the increasing serum ferritin and transferrin saturation.
Conclusions: Our findings suggests that serum ferritin level and transferrin saturation were positively associated with endometriosis. Serum ferritin and transferrin saturation may be an important marker for endometriosis. Future prospective and longitudinal studies are necessary to better understand these findings.
Keywords: Cross-sectional study; Endometriosis; Iron metabolism; Serum ferritin; Transferrin saturation.
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