For further specification, it can be used to calculate red blood cell distribution width.

Red blood cell distribution width (RDW) - the variation in cellular volume of the RBC population.

Twenty two tests were carried out on homozygous mutant mice and one significant abnormality was observed: females had abnormal complete blood count parameters, including an increased red blood cell distribution width and increased mean platelet volume.

The red blood cell distribution width (RDW or RCDW) is a measure of the variation of red blood cell (RBC) volume that is reported as part of a standard complete blood count.

If the anemia is due to iron deficiency, one of the first abnormal values to be noted on a CBC, as the body's iron stores begin to be depleted, will be a high red blood cell distribution width, reflecting an increased variability in the size of red blood cells (RBCs).