THE DISTRIBUTION OF OESTRADIOL IN PLASMA IN RELATION TO UTERINE CROSS‐SECTIONAL AREA IN WOMEN WITH POLYCYSTIC OR MULTIFOLLICULAR OVARIES

Abstract

The uterine cross-sectional area (UXA) of women with polycystic (PCO) or multifollicular ovaries (MFO) is significantly larger and smaller, respectively, than those of normal women during the early-mid-follicular phase of the menstrual cycle. In the present study the distribution of oestradiol in plasma from normal women and women with PCO or MFO was measured to determine if differences in the available fractions of oestradiol could account for the differences in UXA of women with PCO or MFO. No differences in plasma levels of oestradiol were detected and the concentrations of oestradiol present in a free state or bound to albumin were similar in normal women and women with PCO or MFO. The concentration of oestrone was significantly higher in plasma from women with PCO (516 .+-. 120 pmol/l, mean .+-. SD) than in plasma from women with MFO (389 .+-. 91 pmol/l) or normal women (376 .+-. 89 pmol/l). Differences in UXA for women with PCO or MFO as compared with normal women cannot therefore be attributed to differences in available oestradiol concentrations. It is possible that abnormalities in oestrogen metabolism within uterine or other tissues may account for the UXA of women with PCO or MFO. Increased plasma oestrone levels in women with PCO may provide more substrate for conversion to oestradiol within the uterus whilst the smaller UXA of women with MFO may reflect both lack of normal cyclical increases of oestradiol and formation of biologically inactive oestradiol metabolites.