Peritoneal fluid leptin is associated with chronic pelvic pain but not infertility in endometriosis patients

BACKGROUND: Leptin influences the proinflammatory immune responses and has angiogenic activity in vitro and in vivo. The objective of this study was to evaluate the peritoneal fluid levels of leptin in patients with endometriosis and idiopathic infertility and compare them with a control group of tubal ligation/reanastomosis patients. METHODS: In this observational, prospective controlled study, peritoneal fluid from 108 women was obtained while they underwent laparoscopy for pelvic pain, infertility, tubal ligation or sterilization reversal. We measured the concentration of leptin in the peritoneal fluid and compared the levels among women who were divided into groups according to their post-surgical diagnosis. Sixty patients were diagnosed with endometriosis, 10 with idiopathic infertility and 38 had undergone tubal ligation or reanastomosis (control group). RESULTS: Peritoneal fluid leptin was significantly higher in endometriosis 14.62 +/- 9.79 (mean +/- SD) ng/ml compared to idiopathic infertility [0.92 +/- 1.57 ng/ml (P = 0.0007)] and to controls [0.78 +/- 1.94 ng/ml (P < 0.0001)]. Leptin levels were positively correlated with the stage of endometriosis (r = 0.45; P = 0.03), and with pelvic pain in endometriosis patients (r = 0.49; P = 0.001). Peritoneal fluid leptin levels in patients with idiopathic infertility were comparable to controls. CONCLUSIONS: Higher levels of leptin were observed in peritoneal fluid of patients with endometriosis compared to those without the disease. These data suggest that the proinflammatory and neoangiogenic action of leptin may contribute to the pathogenesis of endometriosis. Moreover, leptin may play a role in endometriosis-associated pain.