VARIATION IN RISK INDICATORS OF CARDIOVASCULAR-DISEASE DURING THE MENSTRUAL-CYCLE - AN INVESTIGATION OF WITHIN-SUBJECT VARIATIONS IN GLUTATHIONE-PEROXIDASE, HEMOSTATIC VARIABLES, LIPIDS AND LIPOPROTEINS IN HEALTHY-YOUNG WOMEN

Variations in erythrocyte glutathione peroxidase activity, serum conce ntrations of lipids and lipoproteins and in blood coagulation and fibr inolysis during the menstrual cycle were studied in healthy young wome n. Blood samples were drawn twice a week for 9 weeks. A group of males was used for estimation of the influence on the results of factors wh ich were not related to the menstrual cycle. Variations during the men strual cycle were demonstrated in several of the factors analysed. The activity of glutathione peroxidase was lowest at ovulation. The clott ing activity of factor II+VII+X and the concentration of fibrinogen we re lowest during mid-cycle, and the number of platelets increased in t he follicular phase (days 5-9). Statistically significant variations i n the fibrinolytic factors analysed (tissue plasminogen activator (t-P A) and plasminogen activator inhibitor (PAI)) were not observed during the menstrual cycle. The serum concentrations of cholesterol and LDL cholesterol were significantly higher at the start of the menstrual cy cle (days 3-8) than later in the cycle (days 19-24). The concentration of HDL cholesterol was lowest in the late luteal phase (days 23-28).