Inhibin B and the ovarian follicular reserve

Inhibins are dimeric glycoproteins composed of an α-subunit and a βA-subunit (inhibin A) or βB-subunit (inhibin B), which inhibits pituitary gonadotropin secretion of FSH. The inhibin B is a product of the cohort of antral follicles. The ovarian follicle number decrease steadily as a function of increasing age, with consequent falls in the levels of inhibin B and increase of FSH levels. It is sufficient to maintain ovulatory function and continued secretion of estradiol. Elevated FSH levels seem to occur late in the sequence of events associated with ovarian failure. The inhibin B, produced by granulosa cells, is the earliest marker of the decline in ovarian follicular reserve across reproductive aging.

Inhibin B and ovarian function after total abdominal hysterectomy in women of reproductive age

The aim of this prospective study was to assess ovarian function using clinical and endocrine parameters in women of reproductive age who underwent total abdominal hysterectomy. Sixty-one women, aged ≤ 40 years, were allocated into two groups: group 1, consisting of 31 patients who had hysterectomy, and group 2, consisting of 30 normal women. Inclusion criteria were normal ovarian function at baseline, normal body weight, no hormonal diseases and basal follicle stimulating hormone (FSH) level of < 15 mIU/ml. FSH, luteinizing hormone (LH), estradiol and inhibin B levels as well as maturation value (MV) were measured by vaginal cytology on three occasions: baseline, and 6 and 12 months after hysterectomy. Analysis of variance, the Friedman test, Mann-Whitney test and t-test statistics were employed to compare the two groups. At baseline the groups were homogeneous. At months 6 and 12, hysterectomized women showed decreased median values of inhibin B, increased median values of estradiol (p < 0.05), unchanged median values of FSH and LH, and decreased median values of MV (p < 0.05). In the hysterectomy group, 12.9% (4/31) of the patients had FSH levels of > 40 mIU/ml, estradiol of < 20 pg/ml and inhibin B of < 5 ng/ml, compatible with ovarian failure. In the control group, all the parameters studied remained unchanged. These results suggest that total abdominal hysterectomy accelerates the decline in ovarian function in women of reproductive age.