How do iron deficiency anemia and anemia of chronic disease differ in the context of IBD?

• A. Iron deficiency anemia is due to iron sequestration with high ferritin; anemia of chronic disease is due to blood loss
• B. They are identical
• C. Iron deficiency anemia has high ferritin; ACD has low ferritin
• D. Iron deficiency anemia is due to blood loss and nutritional deficiency; microcytic; low ferritin; anemia of chronic disease is inflammatory with iron sequestration and normal or high ferritin; often normocytic or microcytic

Answer: (D)

Distinguishing these two types of anemia in IBD comes down to cause, iron handling, and what the blood shows on labs. Iron deficiency anemia occurs mainly from chronic gut blood loss and sometimes inadequate iron intake, so iron stores are depleted. That shows up as low ferritin, reflecting little stored iron, and red blood cells tend to be small and pale (microcytic, hypochromic) because there isn’t enough iron to make hemoglobin.

Anemia of chronic disease results from inflammation. Inflammatory signals raise hepcidin, which blocks iron release from macrophages and reduces intestinal iron absorption. The iron is effectively sequestered in storage sites, so ferritin is normal or high (ferritin rises as part of the inflammatory response), even though serum iron is low. The red cells are often normal in size at first (normocytic) and may become microcytic if a concurrent iron deficiency develops.

In short, IDA in IBD is driven by blood loss and depletion of iron stores (low ferritin, microcytosis), whereas anemia of chronic disease is driven by inflammation with iron sequestration (normal/high ferritin, possible normocytic or microcytic indices). In practice, both can overlap in IBD, which can complicate interpretation, but the ferritin pattern and the underlying mechanism are the key distinctions.