Antiphospholipid antibodies

autoimmune production of antibodies against phospholipid, a component of the cell membrane.


a small protein that inhibits coagulation via inactivation of several enzymes of the coagulation system.


a fibrin degradation product (a small protein fragment containing two cross-linked D fragments of the fibrinogen protein that is present in the blood after a blood clot is degraded by fibrinolysis), the levels of which can be determined by a blood test to help diagnose thrombosis. A positive result can indicate thrombosis, but does not rule out other potential causes.


deep vein/venous thrombosis.

Heparin cofactor II

a coagulation factor that inhibits Factor IIa, and is a cofactor for heparin and dermatan sulphate.


hormone replacement therapy.

Hypercoagulable state

an abnormally increased tendency toward blood clotting (coagulation).

International Normalised Ratio

a measure of the time it takes for blood to clot compared with an average. This is an important measure in patients receiving anticoagulant therapy.

Lupus anticoagulant/lupus antibody/lupus inhibitors

Lupus anticoagulant is an immunoglobulin that binds to phospholipids and proteins of the cell membrane. Despite the name, Lupus anticoagulant is actually a prothrombotic agent.


pulmonary embolism.

Protein C/Autoprothrombin IIA/Blood coagulation factor XIV

the inactive form of a protein involved in the coagulation process. Activated protein C is involved in the proteolysis of Factors V and VIII, thereby inhibiting coagulation.

Protein S

protein S is a vitamin K-dependent protein found in the circulation either in its free form or complexed with complement protein C4b, whereby it acts as a cofactor in the inactivation of Factors V and VIII.



von Willebrand factor

a cofactor that interacts with numerous components of the coagulation process, including Factor VIII and platelets.


venous thromboembolism.