What does red blood cell distribution indicate?

The measurement of red blood cell distribution width (RDW) provides crucial insight into the variation in the size of red blood cells (RBCs). A higher RDW indicates greater variability in RBC size, which can be an important diagnostic clue in various hematologic conditions. For instance, it is often elevated in cases of anemia, particularly when there are mixed types of red blood cells, such as microcytic and macrocytic cells present. This variability can point to underlying issues with production or destruction of RBCs, helping clinicians differentiate between various types of anemia and other blood disorders.

Other options do not align with the function of RDW. For instance, the average size of red blood cells is typically assessed by mean corpuscular volume (MCV), not RDW. The percentage of hemoglobin in red blood cells is usually measured by hemoglobin concentration or hematocrit rather than RDW. Finally, the total count of white blood cells is a completely different measurement and not related to red blood cells at all.