Which single laboratory test is the most sensitive and specific screening indicator of iron deficiency anemia?

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

Explanation

Serum ferritin reflects body iron stores and falls early in iron deficiency, before anemia develops. A level below 15 to 30 ng/mL is diagnostic even when other indices are borderline. Serum iron and transferrin saturation fluctuate diurnally and rise in inflammation, while total iron binding capacity rises in iron deficiency but also in pregnancy and oral contraceptive use. Bone marrow iron staining is the gold standard but is invasive, so ferritin remains the best screening test.

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.