title: Influence of oral contraceptives on coagulation tests in native blood and plasma.
abstract: 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.
authors.affiliation: Department of Internal Medicine, University of Innsbruck, Austria.
authors.forename: F
authors.initials: F
authors.lastname: Kunz
authors.forename: C
authors.initials: C
authors.lastname: Pechlaner
authors.forename: M
authors.initials: M
authors.lastname: Tabarelli
authors.forename: E
authors.initials: E
authors.lastname: Sölder
authors.forename: W D
authors.initials: WD
authors.lastname: Zwierzina
mesh_terms: 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
chemical_list: D003278:Contraceptives, Oral, Hormonal