Variations in blood coagulation, fibrinolysis, platelet function and various plasma proteins during the menstrual cycle.

The variations in the number of platelets, platelet retention, blood coagulation, fibrinolysis and various plasma proteins were studied during the menstrual cycle in 30 normal women. Blood samples were taken on 6 occasions; day 1, 2, and 3 of menstruation, day 5-9 (follicular phase), day 12-16 (around ovulation), and day 19-23 (luteal phase), respectively. The concentration of fibrinogen was lower during menstruation than in the luteal phase. Factor II-VII-X and platelet retention were lowest and the recalcification time was shortest during the menstruation. The number of platelets was highest in the ovulatory phase. The fibrinolytic activity was higher in the luteal phase and during the menstruation than in the follicular phase. The results might indicate an intrauterine clotting during the menstruation. The close correlations between the variations of most of the plasma proteins indicate the presence of some general not identified factor which is probably not the variation in the intravascular water content.