Coagulation Disorders USMLE Step 1 Practice Question
A 68-year-old man on broad-spectrum antibiotics for severe pneumonia develops gingival bleeding and prolonged oozing from venipuncture sites. Vital signs: BP 128/76, HR 92, RR 18, Temp 37.2°C, SpO2 98%. PT is prolonged at 18 seconds (normal 12-14); PTT later becomes prolonged. Platelet count is normal at 245,000/μL. He denies melena or hemoptysis. Which of the following best explains his coagulation abnormality?
Answer choices
- AExcessive activation of plasmin causing fibrinolysis
- BDeficiency of von Willebrand factor produced by endothelial cells
- CImmune destruction of platelets
- DDeficiency of fibrinogen synthesis by the liver
- EDeficiency of vitamin K dependent gamma carboxylation of clotting factorsCorrect answer
- FInhibition of thrombin generation by circulating heparin-like substances from gram-negative bacteria
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