Red Cell Distribution Width (RDW)

RDW measures the variation in the size (volume) of red blood cells (RBCs), a phenomenon known as anisocytosis. In a healthy individual, RBCs are relatively uniform in size. RDW is a critical component of the Complete Blood Count (CBC) because it helps differentiate between various types of anemia. For instance, a high RDW with a low Mean Corpuscular Volume (MCV) typically points toward iron deficiency anemia, whereas a normal RDW with low MCV might suggest Thalassemia or anemia of chronic disease. It is also an emerging prognostic marker for cardiovascular health and inflammatory status.