Which condition is most consistent with macrocytic anemia with low B12 and positive anti-intrinsic factor antibodies?

Which condition is most consistent with macrocytic anemia with low B12 and positive anti-intrinsic factor antibodies?

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

Answer: (A)

Pernicious anemia. When macrocytic anemia is accompanied by low vitamin B12 and antibodies against intrinsic factor, it points to autoimmune loss of intrinsic factor, which impairs B12 absorption. The resulting B12 deficiency disrupts DNA synthesis in developing red cells, causing megaloblastic, macrocytic changes. The anti-intrinsic factor antibodies are highly specific for this condition, making pernicious anemia the best explanation. Folate deficiency can also cause macrocytosis but would not show anti-intrinsic factor antibodies or the same pattern of B12 deficiency. Iron deficiency and aplastic anemia do not present with macrocytosis linked to B12 loss.

Pernicious anemia. When macrocytic anemia is accompanied by low vitamin B12 and antibodies against intrinsic factor, it points to autoimmune loss of intrinsic factor, which impairs B12 absorption. The resulting B12 deficiency disrupts DNA synthesis in developing red cells, causing megaloblastic, macrocytic changes. The anti-intrinsic factor antibodies are highly specific for this condition, making pernicious anemia the best explanation. Folate deficiency can also cause macrocytosis but would not show anti-intrinsic factor antibodies or the same pattern of B12 deficiency. Iron deficiency and aplastic anemia do not present with macrocytosis linked to B12 loss.