Decreased levels of peritoneal interleukin-1 receptor antagonist in patients with endometriosis and disease-related dysmenorrhea

OBJECTIVE: To determine the level of interleukin-1 receptor antagonist (IL-1ra) in peritoneal fluid (PF) and serum in patients with endometriosis. DESIGN: A prospective analytical study. SETTING: University-affiliated obstetrics and gynecology academic training hospital. PATIENT(S): One hundred eighteen patients underwent laparoscopy for benign gynecologic diseases. INTERVENTION(S): Peripheral blood and PF were obtained before and during surgical procedures, and the levels of IL-1ra were measured. MAIN OUTCOME MEASURE(S): The concentrations of IL-1ra in PF and serum were correlated with the presence of endometriosis, disease stage, and the phase of menstrual cycle. RESULT(S): Peritoneal fluid IL-1ra concentrations were significantly lower in patients with endometriosis than in patients without endometriosis. Peritoneal fluid IL-1ra concentrations decreased with the increased severity of endometriosis and also decreased in disease-related dysmenorrhea; serum IL-1ra levels showed no significant difference between the patients with and without endometriosis. The concentrations of IL-1ra in PF and serum were not correlated with the phase of menstrual cycle. CONCLUSION(S): Our results suggested that decreased levels of PF IL-1ra in patients with endometriosis and disease-related dysmenorrhea may play an important role in the pathogenesis of this disease.