A 28-year-old woman with menorrhagia has microcytic hypochromic anemia. Which single laboratory parameter best distinguishes early iron deficiency from anemia of chronic disease?

• A Serum iron
• B Transferrin saturation
• C Total iron binding capacity
• D Serum ferritin ✓

Explanation

Serum ferritin reflects storage iron and is the first parameter to fall when body iron stores are depleted, making it the most specific and earliest marker of iron deficiency. Serum iron is low in both iron deficiency and chronic disease, TIBC is high in iron deficiency but low in chronic disease, and transferrin saturation falls late. Ferritin can be falsely elevated by inflammation, so a normal ferritin with strong clinical suspicion may still warrant further testing.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.