Coagulation Disorders USMLE Step 1 Practice Question
A 28-year-old man presents with acute left leg pain and swelling. Vital signs: BP 118/76, HR 92, RR 16, temp 37°C, SpO2 98% on room air. Duplex ultrasound confirms left femoral DVT. Labs show protein C activity 55% (normal 70-150%); D-dimer elevated at 2.8 μg/mL. Family history significant for thrombosis in his mother at age 35. He denies recent immobility, surgery, or malignancy. Which of the following should be considered before initiating anticoagulation therapy?
Answer choices
- AProtein C deficiency is a contraindication to all anticoagulation
- BProtein C levels must reach 100% before any anticoagulation
- CProtein C deficiency may worsen with warfarin monotherapyCorrect answer
- DFactor V Leiden must be ruled out before treatment
- EVitamin K should be given to increase protein C levels
- FWarfarin skin necrosis from protein C rapid depletion before procoagulants
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