What type of anemia is primarily caused by a lack of intrinsic factor?

Pernicious anemia is characterized by the body's inability to absorb vitamin B12 due to a deficiency in intrinsic factor, a protein secreted by gastric parietal cells. Intrinsic factor is essential for the absorption of vitamin B12 in the terminal ileum. Without intrinsic factor, the gut cannot effectively absorb vitamin B12, leading to decreased production of red blood cells and resulting in anemia.

Vitamin B12 is crucial for DNA synthesis in red blood cell production, and its deficiency can lead to megaloblastic anemia, where the red blood cells produced are larger than normal and often dysfunctional. This condition may also show neurological manifestations due to the role of vitamin B12 in maintaining myelin sheaths in the nervous system.

The other types of anemia listed do not primarily relate to intrinsic factor. For instance, iron-deficiency anemia results from inadequate iron for hemoglobin synthesis, aplastic anemia is due to bone marrow failure, and hemolytic anemia involves the premature destruction of red blood cells. Thus, the definition and mechanisms of pernicious anemia clearly point to its association with a lack of intrinsic factor and consequent vitamin B12 deficiency.