Anemias USMLE Step 1 Practice Question
A 23-year-old man with no prior medical history presents with jaundice, dark urine, and severe back pain 2 days after starting trimethoprim-sulfamethoxazole for cellulitis. Vital signs show BP 118/76, HR 102, RR 20, temp 37.8°C, SpO2 98%. Laboratory studies reveal hemoglobin 9.2 g/dL, decreased haptoglobin, elevated lactate dehydrogenase, and elevated indirect bilirubin. Peripheral blood smear demonstrates bite cells. Reticulocyte count is appropriately elevated. Which of the following best explains this patient's disorder?
Answer choices
- AImpaired polymerization of fibrin
- BImpaired conversion of folate to tetrahydrofolate
- CProduction of antibodies against platelet glycoprotein IIb IIIa
- DDefective anchoring proteins in the red cell membrane
- EImpaired generation of reduced glutathione in erythrocytesCorrect answer
- FHereditary spherocytosis
See the full explanation
Get the correct-answer rationale, why each distractor is wrong, the underlying mechanism, and high-yield associations — plus adaptive practice that targets your weak areas — with a free MedBoardPRO account.