Inhibin production has been demonstrated in malignant epithelial ovarian tumours, but secretion of
inhibins by benign
cystadenoma has not yet been reported. The present study evaluated the concentrations of
inhibin A and
inhibin B and the relationship with
oestradiol and
nitric oxide metabolites in fluid collected from benign ovarian
serous cystadenomas (n = 15). In addition, follicular fluid samples (n = 14) from women with regular ovulatory cycles undergoing ovarian stimulation for IVF were studied as a reference group. High concentrations of
inhibin A (median = 89.3 ng/ml) and
inhibin B (median = 116.1 ng/ml) were found in the cystic fluid of ovarian
serous cystadenomas. These
inhibin concentrations were even higher than in follicular fluid of stimulated follicles (
inhibins A and B = 41.2 and 46.8 ng/ml respectively; P: < 0.001), whereas
oestradiol was approximately 18-fold lower in cystic 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 inversely correlated (r = -0.678, P: = 0.008). Cystic fluid samples containing the highest concentrations of NO(2)(-)/NO(3)(-) (45-60 micromol/l) had lower
inhibin A and higher
oestradiol concentrations than those samples containing lower concentrations (10-25 micromol/l) of NO(2)(-)/NO(3)(-). It is concluded that high amounts of dimeric
inhibins are present in ovarian
serous cystadenoma. The source of
inhibins and the determinants of the inverse association of
inhibin A with
oestradiol and
nitric oxide remain to be determined.