Impact of combined hormonal therapy on coagulation inhibitory proteins

The objective of this study was to determine the effect of two combined oral contraceptives on two inhibitory coagulation proteins. The study included 56 women between ages 20 and 55, twenty six of them taking 30µg ethinyloestradiol (EE) and 75µg gestodene (GSD) and thirty of them taking 30 µg ethinyloestradiol and 75 µg levonogestrel (LNG) for two months. The subjects were healthy and they had not taken any other drug two months before starting the hormonal therapy. Plasma was used for measuring protein C and antithrombin III (AT III), before using the pill and after stopping it. Comparison of the values of protein C and AT III between two periods (before and after treatment) showed the following results: Concentrations of protein C was significantly increased while AT III level was decreased after treatment with 30 µg EE/ 75 µg GSD (p=0.001). Treatment with 30 µg EE/ 75 µg LNG showed no significant change in the level of AT III (p=0.058) and significantly increased protein C concentration (p=0.001). We conclude that treatment with 30 µg EE/ 75 µg GSD induces more changes in the inhibitory coagulation proteins than treatment with 30 µg EE/ 75 µg LNG, indicating an increased risk for thrombotic diseases.