A 32-year-old woman with menorrhagia has Hb 9.2 g/dL, MCV 68 fL, low serum iron, high TIBC, and low transferrin saturation. Which single test best confirms true iron deficiency rather than coexisting inflammation?

• A Serum transferrin
• B Serum ferritin ✓
• C Reticulocyte count
• D Serum CRP

Explanation

Ferritin reflects storage iron and is the most specific routine marker of iron deficiency. B low ferritin confirms depleted stores even when the rest of the profile is suggestive. The distractor to kill is serum transferrin: it is elevated in iron deficiency but also rises in chronic disease patterns can overlap, so it is less specific. Ferritin is an acute phase reactant, so a normal value does not exclude deficiency when inflammation is present, but a genuinely low value is diagnostic.

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.