What is the underlying issue in pernicious anemia?

Pernicious anemia is primarily caused by a lack of intrinsic factor, which is a protein produced by the stomach lining that is essential for the absorption of vitamin B12 in the intestines. Vitamin B12 is crucial for the formation of red blood cells and deficiencies can lead to a type of anemia characterized by large, abnormal red blood cells (macrocytic anemia).

Intrinsic factor is necessary for binding to vitamin B12 and facilitating its absorption; without adequate intrinsic factor, vitamin B12 cannot be properly absorbed even if dietary intake is sufficient. As a consequence, the body’s supply of vitamin B12 becomes depleted, leading to impaired red blood cell production and subsequent anemia.

This understanding highlights the importance of intrinsic factor in the pathophysiology of pernicious anemia, and why its absence directly correlates with this condition.