Abstract
To evaluate the physiological significance of inhibin in various types of amenorrhea, serum immunoreactive (IR)-inhibin levels were measured and compared with those in normal cycling women. Amenorrheic women were as follows: (1) 23 women with PCOD, 11 women with hypogonadotropic amenorrhea (HA, n=23) and 11 women with regular menstrual cycles. Women with HA were further divided into 2 groups according to the presence or absence of withdrawal bleeding (WDB) after progesterone administration. HA with WDB was categorized as HA1, while HA without as HA 2. Serum IR-inhibin levels in women with PCOD were significantly higher than those in HA 2 and normal women at days 2 to 5 from the onset of menstruation and significantly lower than those in normal women in the mid-luteal phase. A significant positive correlation was obtained between IR-inhibin and FSH in HA 2 (r=0.681) and HA 1 (r=0.658), but no significant correlation between these two hormones in PCOD and normal women. These results indicated that basal IR-inhibin levels vary with types of amenorrhea. High IR-inhibin levels in PCOD patients suggest that inhibin plays a part in the discordant gonadotropin secretion in these patients.
