Review Question - QID 104153

The patient presents with a deep venous thrombosis (DVT) given her swollen and tender lower extremity. The most common inherited form of hypercoagulability is factor V Leiden.

DVTs are associated with Virchow triad of endothelial injury, venous stasis, and hypercoagulability. In patients without other risk factors for DVT (such as malignancy, pregnancy, or estrogen use), factor V Leiden is the most common cause of a hypercoagulable state. It is caused by a mutation in factor V which prevents it from being inactivated by protein C. This leads to unregulated prothrombin activation and an increase in thrombotic events. Epidemiologically, factor V Leiden is the most common heritable cause of a hypercoagulable state. Patients who have presented with multiple DVTs or pulmonary embolisms may require lifelong anticoagulation.

Figure A depicts the classic appearance of a DVT with a swollen and red lower extremity.

Incorrect Answers:
Answer 1: Antiphospholipid syndrome may present with DVTs or recurrent pregnancy loss and is associated with systemic lupus erythematosus. It is a less common inherited hypercoagulable condition in a Caucasian individual when compared to factor V Leiden.

Answer 2: Antithrombin III deficiency can present with a hypercoagulable state (including DVTs and pulmonary embolisms) but is less common than factor V Leiden. It is a possible but less common inherited condition when compared to factor V Leiden.

Answers 4 & 5: Protein C and S deficiency can cause a hypercoagulable state or may transiently be induced by warfarin use (which inhibits production of protein C and S as well as factors IX, X, VII, and II) which is why a heparin bridge is usually given until the INR is therapeutic. Both of these conditions are less common than factor V Leiden.

Bullet Summary:
Factor V Leiden is the most common heritable hypercoagulable condition.