A 65-year-old woman has macrocytic anemia, loss of vibration sense in the lower limbs, and extensor plantar responses. Which autoantibody, if present, is the most specific for the underlying cause of her anemia?

• A Anti-parietal cell antibody
• B Anti-intrinsic factor antibody ✓
• C Anti-transglutaminase antibody
• D Anti-mitochondrial antibody

Explanation

Subacute combined degeneration with megaloblastic anemia indicates vitamin B12 deficiency, and pernicious anemia is its commonest cause in this age group. Anti-intrinsic factor antibodies are highly specific for pernicious anemia, though less sensitive. Anti-parietal cell antibodies are more sensitive but occur in healthy elderly individuals and atrophic gastritis, so they lack specificity. Anti-transglutaminase suggests celiac disease causing malabsorption, and anti-mitochondrial antibody marks primary biliary cholangitis, unrelated 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.