Anemias USMLE Step 1 Practice Question
A 15-year-old boy with known sickle cell disease comes to the emergency department with severe pain in both legs and lower back after spending the weekend skiing at a high-altitude resort. He is afebrile. Examination shows tenderness over the long bones. Which of the following best explains the trigger for this episode?
Answer choices
- ALoss of red cell membrane phospholipids causing spherocyte formation
- BImpaired heme synthesis from lead-mediated enzyme inhibition
- CPolymerization of deoxygenated hemoglobin S causing red cell sicklingCorrect answer
- DAutoantibody-mediated destruction of erythrocytes in the spleen
- EComplement-mediated lysis due to absence of CD59
- FIncreased expression of fetal hemoglobin due to hypoxic stress at altitude
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