What type of anemia is characterized by an increased RDW?

Anemia characterized by an increased red cell distribution width (RDW) is indicative of variability in red blood cell size, which can occur in certain types of anemia. In iron deficiency anemia, the RDW is often elevated due to the presence of both small, microcytic cells and larger cells called reticulocytes as the bone marrow responds to replenish red blood cell levels. Similarly, in megaloblastic anemia, which is typically due to deficiencies in vitamin B12 or folate, the RDW is also increased because of the production of abnormally large red blood cells (macrocytes) alongside normal-sized cells, leading to further variability in cell size.

Anemia of chronic disease, however, is typically associated with a normal RDW because the red blood cell sizes do not vary significantly in this type of anemia. Instead, it often results in normocytic anemia where the red blood cells are of a consistent size.

Thus, both iron deficiency anemia and megaloblastic anemia prominently feature increased RDW, while anemia of chronic disease does not, making the option indicating that both A and C are responsible for increased RDW the most accurate choice.