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Oral contraceptives, clotting factors, and thrombosis.

Abstract：

:Oral contraceptives (OCs) raise the plasma levels of some clotting factors, especially factor VII. Until recently, however, there has been no evidence for a relationship between high levels of clotting factor and the onset of clinically manifest vascular disease. It has not been established, on a preliminary basis, that high levels of factors VII and VIII and of fibrinogen in men are associated with an increased risk of death from cardiovascular disease. There is a strong relationship between OC estrogen dose and the level of factor VII, a clotting factor with a number of other characteristics, suggesting that high levels would be thrombogenic. A strong relationship also exists between OC estrogen dose and the risk of thromboembolism. The thrombotic effects of OC are probably mediated, at least partly, through their effects on the coagulation system. :Oral contraceptives (OCs) have been related to a number of changes in hemostatic function; theoretically, these changes would increase the risk of thrombosis. The Northwick Park Heart Study (NPHS) prospectively studied the role of the hemostatic system in the pathogenesis of arterial disease and found that in 1510 men aged 40-64 at entry, high levels of each of 3 clotting factors (factors 7 and 8 and fibrinogen) were associated with mortality from cardiovascular disease, particularly ischemic heart disease (IHD). However, these preliminary results do not automatically establish that high levels of clotting factor are of causal significance. Although the general epidemiology of the 3 clotting factors is consistent with the view that high levels are of causal significance, the general epidemiologic characteristics of the individual factors are not identical. Part of the epidemiologic evidence includes the relationship between OC use and factor 7 levels, as well as the lowering of factor 7 levels which can be achieved by dietary measures likely to reduce the risk of clinically manifest IHD. Although the NPHS data on women suggest a trend of increasing factor 7 level with increasing estrogen dose and a strong relationship between OC estrogen dose and risk of thromboembolism, caution should be observed in attributing the factor 7 results entirely to the estrogen dose. This is because progestogens in the most widely used 50 mcg estrogen preparations are not the same as those in 30 mcg estrogen preparation. Nevertheless, it is probable that together with changes in lipids and blood pressure, the OC-related rise in factor 7 and other clotting factors may be one of the mechanisms which increase the risk of thromboembolism in OC users.

journal_name

Am J Obstet Gynecol

journal_title

American journal of obstetrics and gynecology

authors

Meade TW

doi

10.1016/s0002-9378(16)32484-x

subject

Has Abstract

pub_date

1982-03-15 00:00:00

pages

758-61

issue

6 Pt 2

eissn

0002-9378

issn

1097-6868

pii

S0002-9378(16)32484-X

journal_volume

142

pub_type

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Oral contraceptives, clotting factors, and thrombosis.