Reduced hemopexin levels in peritoneal fluid of patients with endometriosis

Objective: To study altered hemopexin concentrations in peritoneal fluid (PF) samples from patients with endometriosis. Recent data implicate a role of altered iron metabolism in endometriosis patients. Hemopexin is the major transport protein for heme. Like iron, heme exposure to the epithelial surface can provoke oxidative stress on the peritoneal epithelium. Therefore, altered hemopexin concentrations and heme scavenging in PF might play a role in the pathophysiology of endometriosis. Design: Prospective explorative study. Setting: Academic tertiary care center. Patient(s): Eighty symptomatic patients scheduled for laparoscopy for the diagnosis and/or therapy of endometriosis. Intervention(s): Aspiration of PF samples during laparoscopy. Main Outcome Measure(s): Hemopexin and heme concentration in PF. Result(s): At laparoscopy, 47 of 80 (58.8%) patients exhibited endometriosis, and 33 (41.2%) were proven disease-free (CO). By means of ELISA significantly lower concentrations of hemopexin in the samples from patients with endometriosis (endometriosis 0.377 ± 0.16 mg/mL) compared with controls (disease-free 0.479 ± 0.20 mg/mL) could be demonstrated. Heme levels in the samples were not significantly different between groups (endometriosis 9.130 ± 6.124 μM and disease-free 9.990 ± 4.485 μM). There was no significant correlation between heme and hemopexin levels (Pearson's correlation coefficient r = -0.146). Demographic data between the groups were comparable. Conclusion(s): These data provide further evidence that hemopexin is significantly down-regulated in PF samples from patients with endometriosis compared with controls. This study confirms recent findings in two-dimensional gel electrophoresis demonstrating a down-regulation of hemopexin in PF from patients with endometriosis in a larger series of samples.