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Iron deficiency anemia from colon cancer — USMLE Step 3 MCQ

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ModerateInternal Medicine (chronic management)Iron deficiency anemia from colon cancerUSMLE Step 3

A 68-year-old man has fatigue and reduced exercise tolerance. Hemoglobin is 9.7 g/dL, MCV is 72 fL, ferritin is 8 ng/mL, stool occult blood testing is positive, and he has lost 4 kg unintentionally. Which of the following is the most likely diagnosis?

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Correct answer: A — Colorectal cancer causing iron deficiency anemia

Iron deficiency anemia in an older man with occult blood loss and weight loss is concerning for colorectal malignancy until evaluated.

Reference: USPSTF colorectal cancer screening; ACG anemia evaluation principles