what does rdw mean on a cbc blood test
Red blood cell distribution width
Red blood cell distribution width ( RDW or RDW - CV or RCDW and RDW - SD ) is a measure of the range of variation of red blood cell ( RBC ) volume that is reported as part of a standard complete blood count . Usually red blood cells are a standard size of about 6 - 8 μm in diameter . Certain disorders , however , cause a significant variation in cell size . Higher RDW values indicate greater variation in size . Normal reference range of RDW - CV in human red blood cells is 11.5 - 14.5 % . If anemia is observed , RDW test results are often used together with mean corpuscular volume ( MCV ) results to determine the possible causes of the anemia . It is mainly used to differentiate an anemia of mixed causes from an anemia of a single cause . 
Red blood cell distribution width ( RDW or RDW - CV or RCDW and RDW - SD ) is a measure of the range of variation of red blood cell ( RBC ) volume that is reported as part of a standard complete blood count . Usually red blood cells are a standard size of about 6 - 8 μm in diameter . Certain disorders , however , cause a significant variation in cell size . Higher RDW values indicate greater variation in size . Normal reference range of RDW - CV in human red blood cells is 11.5 - 14.5 % . If anemia is observed , RDW test results are often used together with mean corpuscular volume ( MCV ) results to determine the possible causes of the anemia . It is mainly used to differentiate an anemia of mixed causes from an anemia of a single cause .
Red blood cell distribution width (RDW) is a measure of the range of variation of red blood cell (RBC) volume that is reported as part of a standard complete blood count.  Certain disorders, however, cause a significant variation in cell size and higher RDW values indicate greater variation in size.
Red blood cell distribution width ( RDW or RDW - CV or RCDW and RDW - SD ) is a measure of the range of variation of red blood cell ( RBC ) volume that is reported as part of a standard complete blood count . Certain disorders , however , cause a significant variation in cell size . Higher RDW values indicate greater variation in size .