Anemias USMLE Step 1 Practice Question
A 51-year-old woman with rheumatoid arthritis on methotrexate presents with progressive fatigue and dyspnea on exertion. Vital signs show HR 98 bpm, BP 128/82 mmHg, RR 20/min, and SpO2 97% on room air. Laboratory findings reveal hemoglobin 9.2 g/dL, MCV 102 fL, and normal reticulocyte count of 0.8%. Serum folate is low at 3.2 ng/mL (normal >5.4), while serum B12 is normal at 450 pg/mL. Which of the following is the most likely diagnosis?
Answer choices
- ARheumatoid arthritis-related anemia
- BMethotrexate-induced folate deficiencyCorrect answer
- CHypothyroidism-induced macrocytosis
- DPernicious anemia
- EHereditary folate malabsorption
- FVitamin B6 deficiency from chronic methotrexate use
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