Which anemia is autoimmune in origin with antibodies to intrinsic factor and parietal cells?

Which anemia is autoimmune in origin with antibodies to intrinsic factor and parietal cells?

• A. Aplastic anemia
• B. Folate deficiency anemia
• C. Pernicious anemia
• D. Iron deficiency anemia

Answer: (C)

Autoimmune pernicious anemia happens when the immune system makes antibodies against intrinsic factor and against gastric parietal cells. Antibodies to intrinsic factor prevent vitamin B12 from binding and being absorbed in the terminal ileum, while parietal cell antibodies lead to autoimmune gastritis and reduced intrinsic factor production. Without sufficient vitamin B12, DNA synthesis in developing red cells falters, causing a macrocytic (megaloblastic) anemia and often neurological symptoms if the deficiency is prolonged. This mechanism specifically ties to antibodies against intrinsic factor and parietal cells, setting pernicious anemia apart from other anemias. Aplastic anemia is a marrow failure with pancytopenia, not driven by intrinsic factor antibodies. Folate deficiency can cause megaloblastic anemia but arises from folate shortage, not autoimmune targeting of intrinsic factor. Iron deficiency anemia is microcytic and due to iron loss or inadequate intake, unrelated to intrinsic factor or parietal cell antibodies.

Autoimmune pernicious anemia happens when the immune system makes antibodies against intrinsic factor and against gastric parietal cells. Antibodies to intrinsic factor prevent vitamin B12 from binding and being absorbed in the terminal ileum, while parietal cell antibodies lead to autoimmune gastritis and reduced intrinsic factor production. Without sufficient vitamin B12, DNA synthesis in developing red cells falters, causing a macrocytic (megaloblastic) anemia and often neurological symptoms if the deficiency is prolonged. This mechanism specifically ties to antibodies against intrinsic factor and parietal cells, setting pernicious anemia apart from other anemias. Aplastic anemia is a marrow failure with pancytopenia, not driven by intrinsic factor antibodies. Folate deficiency can cause megaloblastic anemia but arises from folate shortage, not autoimmune targeting of intrinsic factor. Iron deficiency anemia is microcytic and due to iron loss or inadequate intake, unrelated to intrinsic factor or parietal cell antibodies.