Ovarian-pituitary hormone interactions during the perimenopause

Abstract

To describe the hormone changes that occur at the onset of the perimenopause, daily urine and random blood samples were collected from 5 peri-menopausal women for 3 or 4 consecutive cycles. Estrone conjugate and pregnanediol-3-glucoronide concentrations were determined for urine samples. Circulating luteinizing hormone, follicle stimulating hormone, progesterone, estradiol and estrone concentrations were determined in serum samples. Two of the 5 women experienced irregular menstrual intervals during the study period. One of these subjects experienced a prolonged intermenstrual interval. Three other women exhibited apparently regular ovulatory menstrual cycles. The prolonged intermenstrual interval of one women exhibiting irregular menstrual intervals was associated with low urinary estrogen levels in the early follicular phase of the affected cycle, followed by increased gonadotrophin levels and increased estrogen levels that rose to exceed normal cycle concentrations by 2- or 3-fold. Increased estrogen levels were followed by declining gonadotrophin levels, minimal progesterone production, and, ultimately, vaginal bleeding. These data suggest that there are some forms of menstrual variability at the time of the perimenopause associated with lowered early follicular phase estrogen levels. Reduced negative feedback and subsequently increased gonadotrophin levels may have stimulated estrogen production which may have suppressed gonadotrophin secretion and lowered estrogen excretion, resulting in the observed oscillations between episodes of hypo-and hyperestrogenism.