Influence of oral contraceptives on coagulation tests in native blood and plasma.
Routine coagulation laboratory tests, clotting times in native (not anticoagulated) whole blood, platelet-rich and platelet-poor plasma, and recalcification times in citrated whole blood, platelet-rich and platelet-poor plasma were performed in 14 healthy premenopausal women. Blood was taken before and after one or two cycles of low-dose oral contraceptives. After oral contraceptives a reduction in clotting time in native platelet-rich plasma and activated partial thromboplastin time were observed. Recalcification times in whole blood and platelet-rich plasma were shorter than clotting times in their native counterparts. The observed changes are compatible with a procoagulant effect seen soon after the start of oral contraceptive use. The absence of these changes in the recalcification times in citrate systems suggests a masking effect of citrate. The reduction in clotting times in native platelet-rich but not in platelet-poor plasma indicates that the hypercoagulability in oral contraceptives users is mainly related to platelets.
Kunz
F
F
Department of Internal Medicine, University of Innsbruck, Austria.
Pechlaner
C
C
Tabarelli
M
M
Sölder
E
E
Zwierzina
W D
WD
D001777:Blood Coagulation / Q000187:drug effects*; D001780:Blood Coagulation Tests; D001792:Blood Platelets / Q000187:drug effects; D003278:Contraceptives, Oral, Hormonal / Q000494:pharmacology*; D005260:Female; D006801:Humans; D010314:Partial Thromboplastin Time; D012016:Reference Values; D014914:Whole Blood Coagulation Time
D003278:Contraceptives, Oral, Hormonal