Final answer:
Pernicious anemia results from a lack of intrinsic factor, which is necessary for vitamin B12 absorption. This condition can be caused by various medical issues, including Crohn's disease and some surgeries, and it leads to the production of abnormal red blood cells.
Step-by-step explanation:
Lack of intrinsic factor results in pernicious anemia. Intrinsic factor is a glycoprotein secreted by the stomach that is necessary for the absorption of vitamin B12. Without intrinsic factor, vitamin B12 cannot be absorbed and utilized by the body, leading to vitamin B12 deficiency, which in turn causes pernicious anemia. This type of anemia is characterized by the production of large, abnormal and immature red blood cells (megaloblasts), which lead to reduced oxygen-carrying capacity.
Conditions such as Crohn's disease, certain surgeries, intestinal parasites, and AIDS can lead to a deficiency in intrinsic factor, causing pernicious anemia. Pernicious anemia is often treated with vitamin B12 injections or high doses of oral vitamin B12 supplements. The importance of vitamin B12 is not limited to the production of red blood cells but also extends to neurological function and DNA synthesis.