Which type of anemia in children is associated with normal RDW?

Thalassemia is associated with a normal red cell distribution width (RDW) because it is a type of microcytic anemia that results from an inherited defect in hemoglobin production. In thalassemia, the body produces an abnormal amount of one of the hemoglobin components (either alpha or beta globin chains), leading to a consistent size of red blood cells.

In thalassemia, the red cells are typically uniform in size, which contributes to a normal RDW. This contrasts with other types of anemia, such as iron deficiency anemia, where the RDW is usually elevated due to the presence of varying sizes of red blood cells (microcytes and macrocytes). In vitamin B12 deficiency and sideroblastic anemia, the RDW can also vary significantly because these conditions may lead to asymmetric red blood cell production and variations in size.

Overall, thalassemia presents with a characteristic and consistent size of red blood cells, which is why it is the type of anemia in this context associated with a normal RDW.