Anemias USMLE Step 1 Practice Question
A 7-year-old boy presents with chronic jaundice and progressive fatigue. Vital signs show HR 110/min, RR 22/min, temperature 37.2°C. Laboratory studies reveal hemoglobin 8.2 g/dL, platelet count 120,000/μL, prolonged bleeding time, and elevated indirect bilirubin. Peripheral blood smear demonstrates echinocytes. Coagulation studies are normal. The patient denies recent infections or medication use. Which mechanism best explains this clinical presentation?
Answer choices
- AAutoimmune destruction by splenic macrophages following anti-GpIIb/IIIa binding
- BDecreased NADPH leading to Heinz body formation
- CDefective intrinsic factor production
- DReduced ATP generation impairing red cell membrane integrityCorrect answer
- EImpaired iron incorporation into protoporphyrin
- FAbnormal hemoglobin polymerization causing vaso-occlusive crisis
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