Procoagulant changes induced by oral contraceptives are balanced by an increased fibrinolytic tendency.
Oral contraceptives caused increased fibrinogen, FVII, FX, and fibrinolysis. The latter was associated with elevated FXII and PKK, while C1-INH was decreased, ATIII and alpha 2M were unchanged; it could not be accounted for by changes in t-PA, u-PA, PAI, plasminogen, alpha 2-AP, proteins C or S. HCII and alpha 1-PI were increased and may regulate the availability of thrombin and FXIa. The increased FXII/PKK dependent fibrinolytic potential and HCII may offset any increase in thrombin generation, while alpha 1-PI limits intrinsic coagulation.
Mackie
I J
IJ
Haematology Department, University College and Middlesex School of Medicine, London, U.K.
Campbell
S
S
Gallimore
M
M
Robinson
G
G
Machin
S J
SJ
D000328:Adult; D003276:Contraceptives, Oral; D005167:Factor VII / Q000378:metabolism; D005169:Factor VIII / Q000378:metabolism*; D005170:Factor X / Q000378:metabolism; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D005342:Fibrinolysis; D006801:Humans; D008597:Menstrual Cycle / Q000097:blood
D003276:Contraceptives, Oral; D005167:Factor VII; D005169:Factor VIII; D005170:Factor X; D005340:Fibrinogen