The peritoneal fluid concentration of leptin is increased in women with peritoneal but not ovarian endometriosis

This study was designed to measure leptin concentrations in the peritoneal fluid (PF) of women with different aspects of pelvic endometriosis. Among 36 consecutive women undergoing laparoscopy, nine were diagnosed as having minimal-mild endometriosis (stage I–II). Among nine other subjects with advanced stage (III–IV) disease, six showed one or more ovarian endometriotic cysts as the only operative finding. The remaining 18 unaffected women constituted the control group. Patients with endometriosis had significantly higher PF leptin concentrations (32.6 ± 16.2 versus 17.1 ± 6.6 ng/ml, P = 0.002); this difference remained significant when corrected for body mass index (BMI) (PF leptin/BMI ratio 1.41 ± 0.67 versus 0.76 ± 0.28, P = 0.001). Furthermore, the PF leptin/BMI ratio was significantly higher in women with peritoneal implants than in those in whom no implant was found at laparoscopy (1.6 ± 0.7 versus 0.83 ± 0.33, P = 0.007). Conversely, patients with one or more ovarian endometriomata as the only finding, had a PF leptin/BMI ratio comparable with that in women where no cyst was found (1.05 ± 0.4 versus 1.1 ± 0.65). In women with stage I–II endometriosis, a higher mean PF leptin/BMI ratio was found compared with those affected by stage III–IV (1.78 ± 0.68 versus 1.05 ± 0.43, P = 0.01). These results show that during endometriosis the presence of peritoneal disease, and not of ovarian endometriotic cysts, influences leptin concentrations in PF. The data suggest that leptin may play a role in the development of peritoneal endometriosis, and that different biochemical phenomena might be involved in the pathogenesis of the ovarian form of the disease.