Pernicious anemia can be distinguished from folate deficiency by the presence of what?

Pernicious anemia is an autoimmune condition that results from the inability of the body to absorb vitamin B12 due to a lack of intrinsic factor, which is produced by the gastric parietal cells. One way to confirm the diagnosis of pernicious anemia is by detecting autoantibodies against intrinsic factor. The presence of these autoantibodies indicates that the immune system is attacking the intrinsic factor necessary for vitamin B12 absorption, distinguishing pernicious anemia from folate deficiency, where these autoantibodies would not be present.

Although folate deficiency can also lead to macrocytic anemia, the mechanisms and underlying causes differ from those in pernicious anemia. In folate deficiency, the primary issue is a lack of folate availability, which does not involve the autoimmune aspect seen in pernicious anemia. Therefore, identifying the autoantibodies provides a clear diagnostic marker specific to pernicious anemia, helping to differentiate it from other types of megaloblastic anemia, including those due to folate deficiency.