Oral contraceptives, ABO blood groups, and in vitro fibrin formation.
The relation between oral contraceptive (OC) use, ABO blood groups, and in vitro fibrin formation, as measured by thromboelastography, was investigated in 4315 women. The thromboelastogram (TEG) measures the speed of fibrin formation (R, K) and clot firmness (Ma). More rapid fibrin formation and increased clot firmness were associated with current OC use, but not to the extent seen in pathologic states. This relation was not related to dose, estrogen-progestin type, or duration of exposure. Past and "never" OC users had similar TEG values, suggesting reversibility, and noncontraceptive estrogens had a minimal effect on the TEG. ABO blood groups were found to have only a slight association with TEG values. Subjects with blood group O showed a somewhat prolonged speed of fibrin formation as compared to all other subjects. A decreased clot firmness was found in AB subjects, but this did not persist among OC users.
D000017:ABO Blood-Group System; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001777:Blood Coagulation / Q000187:drug effects*; D003276:Contraceptives, Oral / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D005337:Fibrin / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D013916:Thrombelastography; D013997:Time Factors
D000017:ABO Blood-Group System; D003276:Contraceptives, Oral; D004967:Estrogens; D005337:Fibrin