A 34-year-old woman with heavy menstrual bleeding has Hb 9.8 g/dL, MCV 68 fL, high RDW, low serum iron, and elevated transferrin saturation below normal range. Which single test best distinguishes true iron deficiency from anemia of chronic disease?

• A Bone marrow Prussian blue stain
• B Serum transferrin receptor concentration
• C Serum ferritin ✓
• D Peripheral smear for microcytosis

Explanation

Serum ferritin reflects storage iron and is the single best screening discriminator: it is low in iron deficiency and normal or raised in anemia of chronic disease because ferritin is an acute phase reactant. Transferrin receptor rises in both conditions when erythropoietic drive increases, so it does not separate them cleanly. Marrow iron staining is the gold standard but is invasive and not the screening test asked for here.

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.