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Protein C Deficiency


Step 1: View clinicals

A 25 year old man presents for further workup of an episode of venous thromboembolism. He developed deep vein thrombosis (DVT) of the left lower limb approximately 4 months ago. Prior to this, he had been sitting in one place for 12 hours, during an airplane flight. At that time, multiple investigations were performed, including a complete blood count, peripheral blood smear, and liver and renal profiles. No obvious cause for the thrombotic episode could be discerned. He was then started on heparin and warfarin, with the former discontinued once his INR reached satisfactory levels. The latter was continued for 3 months in total, and stopped 1 month ago. There is no family history of thrombotic disorders, and he was apparently healthy earlier, with unremarkable medical, surgical, and drug histories.

Step 2: Order all relevant investigations

Complete Blood Count + Liver Profile

The complete blood count and liver profile are both within normal parameters.

Coagulation Profile

PT: 13 sec (11-13.5) INR: 0.9 (0.8-1.1) aPTT: 36 sec (28-38) TT: 16 sec (15-19)

ANA + Antiphospholipid Abs

ANA: 0.3 U/L (< 1.0) Lupus anticoagulant: negative Anticardiolipin antibodies: negative Anti-β2-glycoprotein-I antibodies: negative

Genetic Thrombophilia Screen

Protein C Activity: 32% of normal Protein S activity: normal Antithrombin III activity: normal Activated Protein C resistance ratio: within normal range Factor VIII concentration: normal Fibrinogen concentration: normal Serum Homocysteine levels: normal FII G20210A mutation analysis: negative

Step 3: Select appropriate management

Lifelong Warfarin Therapy
Lifelong Aspirin Therapy
Screen Family Members
Prophylactic FFP each month

Score: ★★☆