Anemias USMLE Step 1 Practice Question
A 23-year-old man develops jaundice, dark urine, and fatigue 2 days after starting trimethoprim-sulfamethoxazole for a skin infection. He has no previous medical history. Laboratory studies show decreased hemoglobin, elevated lactate dehydrogenase, and elevated indirect bilirubin. Peripheral smear demonstrates bite cells. Which of the following best explains the pathogenesis of this condition?
Answer choices
- ALoss of CD55 and CD59 on blood cells
- BDecreased NADPH production leading to oxidative damage of hemoglobinCorrect answer
- CReduced synthesis of the beta-globin chain
- DAutoimmune IgM-mediated agglutination at cold temperatures
- EDefective DNA synthesis due to impaired thymidylate production
- FHereditary spherocytosis
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