High concentrations of inhibin A and inhibin B in ovarian serous cystadenoma: relationship with oestradiol and nitric oxide metabolites

Inhibin production has been demonstrated in malignant epithelial ovarian tu mours, but secretion of inhibins by benign cystadenoma has not yet been rep orted. The present study evaluated the concentrations of inhibin A and inhi bin B and the relationship with oestradiol and nitric oxide metabolites in fluid collected from benign ovarian serous cystadenomas (n = 15). In additi on, follicular fluid samples (n = 14) from women with regular ovulatory cyc les undergoing ovarian stimulation for IVF were studied as a reference grou p. High concentrations of inhibin A (median = 89.3 ng/ml) and inhibin B (me dian = 116.1 ng/ml) were found in the cystic fluid of ovarian serous cystad enomas. These inhibin concentrations were even higher than in follicular fl uid of stimulated follicles (inhibins A and B = 41.2 and 46.8 ng/ml respect ively; P< 0.001), whereas oestradiol was <similar to>18-fold lower in cysti c fluid than in follicular fluid (median = 34 versus 622 pg/ml, P< 0.001). In ovarian cysts, the concentrations of inhibin A and oestradiol were inver sely correlated (r = -0.678, P = 0.008). Cystic fluid samples containing th e highest concentrations of NO2-/NO3- (45-60 mu mol/l) had lower inhibin A and higher oestradiol concentrations than those samples containing lower co ncentrations (10-25 mu mol/l) of NO2-/NO3-. It is concluded that high amoun ts of dimeric inhibins are present in ovarian serous cystadenoma. The sourc e of inhibins and the determinants of the inverse association of inhibin a with oestradiol and nitric oxide remain to be determined.