What is the cause of pernicious anemia?

Pernicious anemia specifically arises from a deficiency of vitamin B12, primarily due to a lack of intrinsic factor, a protein necessary for vitamin B12 absorption in the intestines. Intrinsic factor is secreted by the gastric mucosa, and when there is damage to the gastric lining due to conditions such as autoimmune gastritis, this can lead to decreased secretion of intrinsic factor. Consequently, this impairment prevents the adequate absorption of vitamin B12, leading to the development of pernicious anemia.

While vitamin B12 is essential for red blood cell production, its deficiency causes similar symptoms to other types of anemia, but the underlying cause is distinct. Recognizing that pernicious anemia is specifically linked to intrinsic factor deficiency allows for appropriate diagnosis and treatment, typically with vitamin B12 supplementation, either through diet or injections.

Other options may describe various anemia types or related issues but do not address the specific mechanism of pernicious anemia and its link to intrinsic factor and vitamin B12 absorption effectively. For example, options discussing MCV or hemoglobin levels may apply to different types of anemia or conditions, making them less relevant in the context of pernicious anemia.