The modified radioimmunoassay of serum inhibin and its value in monitoring ovarian tumor

Objectives and Methods: A modified radioimmunoassay (RIA) of serum inhibin (INH) was developed and applied to measure serum INH contents in 39 fertile and 16 postmenopausal women. Thirty-three cases of ovarian tumors, including granulosa cell tumors and other kinds of ovarian tumors, were monitored by serum INH RIA. Results: The mean value of serum INH contents in follicular, peri-ovulatory and mid-luteal phases of fertile women were 9.48±7.10 pg/ml (2.04∼18.53pg/ml), 19.04±9.73 pg/ml (3.49∼33.26 pg/ml) and 131.13±110.81 pg/ml (3.49∼ 341.10 pg/ml), respectively. Serum INH concentration was negatively correlated with serum FSH concentration, (r_s=−0.483,P<0.01). Serum IHN contents were less than 3.6 pg/ml in normal postmenopausal women. The mean value of serum INH contents in ovarian granulosa cell tumor, thecoma, mucinous cystadenocarcinoma and malignant teratoma cases were significantly higher than that of other ovarian tumors, (P<0.01). Serum INH contents were elevated in ovarian granulosa cell tumor, thecoma, mucinous cystadenocaricinoma and endometrioid carcinoma cases with serum CA-125 values in normal range before operation, but serum INH contents decreased to normal range within one week after operation. And consecutive serum INH RIA could be a valuable tool in monitoring for therapeutic effect. Conclusion: Modified INH RIA was of convenient, time-saving and quantitative characteristics, especially with its high sensitivity (<1 pg/ml). There was a regular change of serum INH concentrations during menstrual cycle. INH could inhibit the synthesis and secretion of follicle stimulating hormone (FSH). INH would become a valuable marker for ovarian tumor. INH RIA combined with the measurement of serum CA-125 would be helpful to the early diagnosis, treatment and follow-up for ovarian cancer.