TF and endometriosis: The PF of patients with endometriosis (n = 41) showed significantly higher iron concentrations (16.67 vs. 10.13 μmol/L; P < 0.001), ferritin concentrations (416.6 vs. 79.10 ng/mL; P < 0.001) and transferrin saturation (51.93% vs. 32.25%; P < 0.001) than those of the controls (n = 31; Fig. 1A–C).