ABSTRACT
Levels of inhibin A and B as well as other hormones in serum samples obtained during the pill-free interval in women taking combined oral contraceptives (OC) were measured to asses the extent of ovarian activity during that period. Type of pill and day of pill-free interval were recorded during routine gynecologic check-ups, if patients were in the pill-free period and had taken their pills regularly in the previous cycle. In addition to inhibin A and B, serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), and progesterone were also quantified. Inhibin B levels rise significantly in parallel with rising levels of FSH, LH, and E2. Progesterone levels were completely suppressed and inhibin A levels rose slightly but insignificantly. Inhibins are sensitive biochemical markers of ovarian activity in pill-free intervals.
PIP: Serum values of dimeric inhibin A and B were measured to assess the restoration of pituitary and ovarian activity during the pill-free interval in women taking combined oral contraceptives. 175 healthy women 18-35 years of age from five areas in Belgium were enrolled and monitored during routine gynecologic examinations. During the 7 day pill-free interval, inhibin B levels rose significantly in parallel with rising levels of follicle-stimulating hormone, luteinizing hormone, and estradiol. Progesterone levels were completely suppressed. Inhibin A levels rose slightly but insignificantly, reflecting an absence of development of preovulatory follicles. These findings indicate that inhibins are sensitive biochemical markers of ovarian activity in pill-free intervals. Inhibin B appears to be predominantly a product of the cohort of developing primary and subsequent early antral follicles, while inhibin A secretion is more indicative of dominant follicular and corpus luteum function.
