In a patient with suspected pernicious anemia, which laboratory finding is the most specific for establishing the diagnosis?

• A Anti-parietal cell antibodies
• B Low serum gastrin
• C Anti-intrinsic factor antibodies ✓
• D Positive Schilling test after intrinsic factor administration

Explanation

Anti-intrinsic factor antibodies are found in about 50 to 70 percent of patients with pernicious anemia and are highly specific, essentially occurring only in this disease. Anti-parietal cell antibodies are more sensitive but lack specificity, being present in atrophic gastritis, thyroid disease, and many healthy elderly individuals. Gastrin is elevated, not low, because achlorhydria removes acid-mediated feedback inhibition. The Schilling test is historically classic but is no longer available in most centers, so intrinsic factor antibodies carry the diagnostic weight.

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.