The coefficient of variation of red blood cell distribution width, referred to as RDW in routine blood reports, is a parameter that reflects the size of the red blood cell volume. If in a normal person without anemia, the distribution width graph is a very nice normal distribution graph. If the graph is significantly shifted to the left, it mostly suggests a small cell hypochromic anemia, which is a common clinical condition called iron deficiency anemia. If the normal distribution graph is shifted to the right, the clinical suspicion is large cell hyperchromic anemia, which is often referred to as megaloblastic anemia, or myelodysplastic syndrome MDS, etc. The distribution width coefficient RDW is generally normally distributed, and in the normal range of distribution, it usually suggests that the patient is not anemic.