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Iron deficiency anemia — USMLE Step 3 MCQ

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ModerateAmbulatory Medicine / Primary CareIron deficiency anemiaUSMLE Step 3

A 67-year-old man is found to have fatigue and microcytic anemia. Ferritin is 9 ng/mL and stool guaiac is positive. He eats a varied diet and takes no anticoagulants. Which of the following is the most likely diagnosis?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: E — Occult gastrointestinal blood loss

Iron deficiency anemia in an older man should prompt evaluation for occult gastrointestinal bleeding, including malignancy.

Reference: American Gastroenterological Association iron deficiency anemia guidance