INCREASE OF HIGH-DENSITY-LIPOPROTEIN CHOLESTEROL AT OVULATION IN HEALTHY WOMEN

Plasma cholesterol is believed to vary more in women than in men, with the menstrual cycle, yet our review of the literature found no consis tent pattern. We examined variations in plasma lipoproteins in relatio n to ovarian hormones in 12 healthy, menstruating women. Twenty fastin g blood samples were obtained on alternate days over one menstrual cyc le; ovulation was timed by hormone measurements. Plasma was analysed e nzymatically for total cholesterol (TC), high-density lipoprotein chol esterol (HDL-C) and triacylglycerol (TAG). Low-density lipoprotein cho lesterol (LDL-C) was estimated by the Friedewald formula. The greatest effect was seen in HDL-C. Concentrations increased by 12% (P < 0.001) between the times of menstruation and ovulation and remained elevated until the following premenstrual phase. The height of peak oestradiol concentrations at ovulation was significantly associated with HDL-C i n that phase (r = +0.75, P < 0.01), and with mean HDL-C concentrations over the whole cycle (r = +0.65, P < 0.05). TC and LDL-C also increas ed at ovulation, by 9% (P < 0.005) and 11% (P < 0.025) respectively, a lthough the effect was more transient. This study demonstrates that co nsistent changes in plasma lipoproteins do occur during the menstrual cycle.