What is the primary cause of pernicious anemia?

Pernicious anemia is primarily caused by the autoimmune destruction of the parietal cells in the stomach. These parietal cells are responsible for producing intrinsic factor, a protein that is essential for the absorption of vitamin B12 in the intestines. When these cells are damaged or destroyed by an autoimmune response, the production of intrinsic factor is significantly reduced or absent. This leads to decreased absorption of vitamin B12 from dietary sources, resulting in vitamin B12 deficiency and eventually causing pernicious anemia.

This autoimmune component makes pernicious anemia distinct from other types of anemia, which may have different underlying mechanisms. It is critical to understand that unlike dietary insufficiency, which could lead to vitamin B12 deficiency in a general sense, pernicious anemia specifically stems from the inability to absorb vitamin B12 due to the lack of intrinsic factor caused by the destruction of the parietal cells. This specificity highlights the unique nature of pernicious anemia compared to other forms of anemia linked to nutritional deficiencies or other causes.