In a patient who recently had a gastrectomy, which type of anemia is of concern due to lack of intrinsic factor?

• A. Aplastic
• B. Pernicious
• C. Iron deficiency
• D. Nutritional

Answer: (B)

Loss of intrinsic factor after gastrectomy prevents vitamin B12 absorption. Intrinsic factor binds vitamin B12 in the stomach so it can be absorbed later in the small intestine; without it, B12 deficiency develops. Vitamin B12 is essential for DNA synthesis in red blood cell precursors, so its deficiency leads to ineffective and abnormal erythropoiesis with large, immature red cells—megaloblastic anemia. This specific situation is pernicious anemia, defined by B12 deficiency due to lack of intrinsic factor rather than a failure of the bone marrow or iron supply. Aplastic anemia involves bone marrow failure and pancytopenia; iron deficiency anemia is a microcytic process from iron shortage; nutritional anemia is a broad category that can include various deficiencies but does not center on intrinsic factor.