Which type of anemia is characterized by low serum iron and low transferrin saturation?

Anemia of chronic disease is characterized by low serum iron and low transferrin saturation due to the body's response to chronic inflammation or infection. In this condition, inflammatory cytokines, particularly interleukin-6, lead to increased hepcidin production from the liver. Hepcidin reduces intestinal iron absorption and sequesters iron in macrophages, making it less available for erythropoiesis. This results in a low serum iron level and low transferrin saturation, as the circulating iron is diminished, despite the body having adequate or even increased stores of iron in macrophages and the liver.

In contrast, iron-deficiency anemia typically presents with low serum iron, low transferrin saturation, and reduced ferritin, indicating depleted iron stores. Vitamin B12 deficiency anemia and pernicious anemia primarily involve deficiencies in vitamin B12, leading to megaloblastic changes in erythrocytes, which do not primarily affect serum iron and transferrin saturation in the same way. Thus, the distinct profile of low serum iron and low transferrin saturation is specifically indicative of anemia of chronic disease.