A 50-year-old woman with rheumatoid arthritis has hemoglobin 9.5 g/dL, MCV 78 fL, serum iron low, transferrin saturation 12%, TIBC low, and ferritin 180 ng/mL. Which mediator best explains this pattern?

• A Interleukin 6 induced hepatic hepcidin release trapping iron in macrophages ✓
• B Erythropoietin excess causing iron wasting
• C Autoantibody mediated destruction of ferroportin on enterocytes only
• D Vitamin B6 deficiency blocking ALA synthase

Explanation

In anemia of chronic inflammation, IL 6 drives hepatic hepcidin secretion, and hepcidin binds ferroportin on macrophages and enterocytes, causing its internalization. Iron is therefore sequestered in macrophages, giving low serum iron, low TIBC, and high ferritin as an acute phase reactant. The combination of low TIBC with adequate ferritin distinguishes it from true iron deficiency, where TIBC is high and ferritin is low.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

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