Ovarian sensitivity to follicle-stimulating hormone during the follicular phase of the human menstrual cycle and in patients with polycystic ovarian syndrome.

OBJECTIVE

To investigate the existence of a different sensitivity of ovaries to follicle-stimulating hormone (FSH) during the follicular phase of the human menstrual cycle and in patients with polycystic ovarian syndrome (PCOS).

DESIGN

Thirty-four normal subjects and 13 patients with PCOS were treated intravenously by FSH (75 or 225 IU) or saline at different stages of follicular phase.

MAIN OUTCOME MEASURES: Plasma levels of luteinizing hormone (LH), FSH, estradiol (E2), and testosterone (T) in samples collected for a period of 26 hours after the injection.

RESULTS

In patients at the early stages of follicular phase (baseline E2 < 50 pg/mL), FSH increased in dose-dependent manner E2 and E2:T-stimulated area under curve (AUC) in respect to saline experiments. In PCOS subjects, saline E2, and E2:T-stimulated AUC were significantly lower than normal women. Follicle-stimulating hormone (75 IU) dramatically increased these values, and no difference was seen in respect to 75 and 225 IU FSH-treated controls. In patients with E2 baseline plasma levels > 50 pg/mL, FSH (75 or 225 IU) failed to increase both E2 and E2:T-stimulated AUC in comparison with saline studies.

CONCLUSIONS

Early stages of follicular phase in normal and polycystic ovaries are the most responsive to the elevation of circulating FSH levels, whereas the ovarian sensitivity spontaneously decreases as follicular maturation enhances.