Factor V antigen levels and venous thrombosis: risk profile, interaction with factor V leiden, and relation with factor VIII antigen levels.

Abstract

Clotting factor V has a dual function in coagulation: after activation, procoagulant factor V stimulates the formation of thrombin, whereas anticoagulant factor V acts as a cofactor for activated protein C (APC) in the degradation of factor VIII/VIIIa, thereby reducing thrombin formation. In the present study, we evaluated whether plasma factor V levels, either decreased or increased, are associated with venous thrombosis. High procoagulant factor V levels may enhance prothrombinase activity and increase the thrombosis risk. Low anticoagulant factor V levels could reduce APC-cofactor activity in the factor VIII inactivation (APC-resistant phenotype), which might also promote thrombosis. Low factor V levels in combination with factor V Leiden could lead to a more severe APC-resistant phenotype (pseudohomozygous APC resistance). To address these issues, we have measured factor V antigen (factor V:Ag) levels in 474 patients with thrombosis and 474 control subjects that were part of the Leiden Thrombophilia Study (LETS). Factor V:Ag levels increased by 7.6 U/dL for every successive 10 years of age. Mean factor V:Ag levels were 134 (range 41 to 305) U/dL in patients and 132 (range 47 to 302) U/dL in controls. Neither high nor low factor V:Ag levels were associated with venous thrombosis. We found that factor V:Ag and factor VIII antigen levels in plasma were correlated, but factor V did not modify the thrombotic risk of high factor VIII levels. The normalized APC ratio was not influenced by the factor V:Ag level in subjects with or without factor V Leiden. We conclude that neither low nor high factor V:Ag levels are associated with venous thrombosis and that factor V:Ag levels do not mediate the thrombotic risk associated with high factor VIII levels.

• Authors: P W Kamphuisen, F R Rosendaal, J C Eikenboom, R Bos, R M Bertina
• Journal: Arteriosclerosis, thrombosis, and vascular biology (Arterioscler Thromb Vasc Biol) Vol. 20 Issue 5 Pg. 1382-6 (May 2000) ISSN: 1079-5642 [Print] United States
• PMID: 10807757 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Protein C
• factor V Leiden
• Factor V
• Factor VIII

Topics

• Adolescent
• Adult
• Aged
• Drug Resistance
• Factor V (metabolism)
• Factor VIII (metabolism)
• Female
• Humans
• Male
• Middle Aged
• Protein C (physiology)
• Risk Factors
• Venous Thrombosis (blood)