RDW 12 - 16


This is a measure of the degree of variation in the size of red blood cells (anisocytosis) in a given population. The normal range for the RDW is 11. 8 to 15. 8. The RDW is elevated in association with many anemias. However, it is a very useful measurement when differentiating between iron deficiency anemia or thalassemia as the cause of a microcytic anemia with a low reticulocyte index. If the RDW is elevated with a microcytic anemia, the cause is most likely iron deficiency anemia, as opposed to thalassemia, which usually presents with a normal RDW.