Anemias USMLE Step 1 Practice Question
A 63-year-old woman presents with progressive fatigue, glossitis, and paresthesias in both hands. Vital signs: BP 128/76, HR 92, RR 18, Temp 37°C, SpO2 98% on room air. Laboratory studies reveal macrocytic anemia (Hb 9.2 g/dL, MCV 108 fL), elevated methylmalonic acid, and positive anti-intrinsic factor antibodies. Peripheral blood smear shows hypersegmented neutrophils. She denies alcohol use. Which of the following best describes the underlying mechanism of her anemia?
Answer choices
- AAutoimmune destruction of gastric parietal cells leading to intrinsic factor deficiencyCorrect answer
- BLoss of the PIGA gene
- CReduced hepcidin production causing iron overload
- DDeficiency of ALA synthase
- EDefective ileal bile acid transport
- FImpaired conversion of 5-methyltetrahydrofolate to tetrahydrofolate due to cobalamin deficiency
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