Coagulation Disorders USMLE Step 1 Practice Question
A 26-year-old woman presents with petechiae and easy bruising two weeks after a viral upper respiratory infection. Vital signs are stable (BP 118/76, HR 82, RR 16, Temp 37°C). Physical examination reveals scattered petechiae on her lower extremities; splenomegaly is absent. Laboratory studies show platelet count of 14,000/mm³, hemoglobin 13.2 g/dL, and WBC 7,200/mm³. Coagulation studies are normal. She denies recent medication use. Which of the following is the most likely mechanism of her thrombocytopenia?
Answer choices
- AAutoantibodies against platelet glycoproteins causing splenic clearanceCorrect answer
- BDeficiency of ADAMTS13 leading to platelet rich microthrombi
- CSuppression of all bone marrow cell lines by toxic injury
- DDeficiency of vitamin K dependent clotting factors
- EConsumption of clotting factors by widespread tissue factor activation
- FAbnormal splenic sequestration of platelets due to increased vascular permeability
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