Pernicious anemia is treated with supplementation of which vitamin when intrinsic factor is deficient?

Pernicious anemia is treated with supplementation of which vitamin when intrinsic factor is deficient?

• A. Vitamin C
• B. Iron
• C. Vitamin B12
• D. Folate

Answer: (C)

Intrinsic factor is required for absorbing vitamin B12 in the terminal ileum, so when intrinsic factor is deficient—as in pernicious anemia—the body can’t absorb B12 from the gut. The treatment is to replace vitamin B12 directly, bypassing the need for intrinsic factor, usually with parenteral injections (cyanocobalamin or hydroxocobalamin). This corrects the B12 deficiency that drives the anemia and any associated neurologic issues. Iron targets iron deficiency, and folate can improve red cell counts but won’t fix B12 deficiency and can mask its neurologic effects; Vitamin C has no role here.

Intrinsic factor is required for absorbing vitamin B12 in the terminal ileum, so when intrinsic factor is deficient—as in pernicious anemia—the body can’t absorb B12 from the gut. The treatment is to replace vitamin B12 directly, bypassing the need for intrinsic factor, usually with parenteral injections (cyanocobalamin or hydroxocobalamin). This corrects the B12 deficiency that drives the anemia and any associated neurologic issues. Iron targets iron deficiency, and folate can improve red cell counts but won’t fix B12 deficiency and can mask its neurologic effects; Vitamin C has no role here.