A 60-year-old vegetarian man has macrocytic anemia, hypersegmented neutrophils, paresthesias of both feet, loss of vibration sense, and extensor plantar responses. Serum methylmalonic acid is elevated. Which treatment corrects the neurological findings?

• A Oral folic acid alone
• B Parenteral vitamin B12 ✓
• C Oral iron plus folic acid
• D Pyridoxine supplementation

Explanation

The combination of megaloblastic anemia with subacute combined degeneration of the cord and elevated methylmalonic acid indicates vitamin B12 deficiency. Only B12 replacement treats the neurologic damage; hematologic response may occur with folate, but folate alone masks the anemia while neurologic deficits progress, making option A the classic trap. Iron and pyridoxine address other anemia mechanisms entirely and have no role 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.