Pernicious anemia is due to deficiency of which factor?

Pernicious anemia is due to deficiency of which factor?

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

Answer: (A)

Intrinsic factor is the carrier protein produced by gastric parietal cells that binds vitamin B12 and enables its absorption in the terminal ileum. Pernicious anemia arises when intrinsic factor production is deficient, usually from autoimmune destruction of parietal cells or antibodies against intrinsic factor. Without this factor, vitamin B12 cannot be absorbed properly, leading to B12 deficiency and the characteristic megaloblastic anemia with potential neurological symptoms. The other options involve nutrients or deficiencies that don’t hinge on the absorption carrier: folate and iron deficiencies cause different anemias, and vitamin B12 deficiency can occur from many causes other than intrinsic factor loss, but pernicious anemia specifically centers on the lack of intrinsic factor.

Intrinsic factor is the carrier protein produced by gastric parietal cells that binds vitamin B12 and enables its absorption in the terminal ileum. Pernicious anemia arises when intrinsic factor production is deficient, usually from autoimmune destruction of parietal cells or antibodies against intrinsic factor. Without this factor, vitamin B12 cannot be absorbed properly, leading to B12 deficiency and the characteristic megaloblastic anemia with potential neurological symptoms. The other options involve nutrients or deficiencies that don’t hinge on the absorption carrier: folate and iron deficiencies cause different anemias, and vitamin B12 deficiency can occur from many causes other than intrinsic factor loss, but pernicious anemia specifically centers on the lack of intrinsic factor.