Coagulation Pathways : Wheeless' Textbook of Orthopaedics

- See:
- deep venous thrombosis
- hypercoagulable states

- Specific Factors:
- fibrinogen (factor I);
- prothrombin (factor II)
- converts finbrinogen to fibrin
- activates V, VIII & XIII (when bound to thrombomodulin)
- activates protein C;
- Vit K dependent;
- factor V:
           - when activated, serves as enzyme co-factor;
           - mutation leads to Leiden thrombophilia (decreased inactivation of factor V and thus a greater tendency to form clots)
           - ref: Factor V Leiden Thrombophilia
    - factor Xa: part of Xa/Va complex which activates prothrombin;
- factor VII:
- part of factor VII/tissue factor complex that activates factor X and IX;
- is activated by Xa;
- Vit K dependent;
- factor VIII: serves as enzyme cofactor to help activate factor X;
           - deficiency of this factor leads to hemophilia
    - factor IX:
- acts w/ IXa/VIIIa/phos complex that activates factor X;
- Vit K dependent;
- factor X:
- acts as Xa/Va phos complex that actives prothrombin;
           - this factor is inhibited by lovenox and other low molecular wt heparins;
           - Vit K dependent;
           - see lovenox and rivaroxaban
           - ref: The mechanism of action of rivaroxaban--an oral, direct Factor Xa inhibitor--compared with other anticoagulants.
    - factor XII:
- protein C:
- when activated to Ca by thrombin bound to thrombomodulin, inhibits by proteolysis factors VIIIa and Va in reactions
                  requiring prot S and phospholipids as cofactors; Vit K dependent;
- antithrombin III:
- is a plasma protease inhibitor that serves as a protease scavenger;
- any of the blood-clotting enzymes that move away from the growing clot rapidly form a complex, and their activities are
                       neutralized
- formation of complexes is accelerated by heparin, forms of which are located in the microvasculature on the surfaces of
                       endothelial cells;
- inhibitor of the enzymes thrombin, Xa, IXa; Is activated by heparin
           - see arixtra

Medical Progress: The regulation of hemostasis: the protein C system.

Deficiencies of coagulation-inhibiting and fibrinolytic proteins in outpatients with deep-vein thrombosis.

Prevention of venous thrombosis after total hip arthroplasty. Antithrombin III and low-dose heparin compared with dextran 40.

The effect of total hip replacement and general surgery on antithrombin III in relation to venous thrombosis.

Coffee consumption is associated with a reduced risk of venous thrombosis that is mediated through hemostatic factor levels

Review Article: Seminars in Medicine of the Beth Israel Hospital, Boston: Molecular and cellular biology of blood coagulation.