RDW (RED CELL DISTRIBUTION WIDTH) has to do with the Red blood cells, shape, size, volume, etc.

Abnormal results, depending on what is happening physically, may trigger other tests that doctors need more info to diagnosis or monitor.

Normal Ranges of RDW
Men 11.5%-14.5%
Women 11.5%-14.5%
Children 11.5% – 14.5%

RDW is often looked at when  trying to find the source of possible causes of anemia, aka. low Red Blood Cells, aka low Hgb.

There are variable’s within the test results, based on the patients age,  lab equipment used in testing, and other factors.  This test should not be a point of focus or used as a stand alone result, to make any diagnosis.  Further testing is required.

High RDW generally indicates Red Blood Cells are not equal in size. Possibly indicating the body is having trouble producing Red Blood Cells.  Since Red Cell production is a function of the Bone Marrow.  Abnormal RDW test results often lead to testing in that direction.  That Bone Marrow function also consumes Iron and Vitamin B12.  So further testing in that area may be necessary to identify a deficiency there.

If RDW is tested as high.  Often MCV will then be tested, if it wasn’t at the time of the RDW..   RDW and MCV are closely related.  MCV = Mean Corpuscular Volume.  MCV measures the average size of your Red Blood Cells.

High RDW with High MCV may indicate a liver disease, Hemolytic Anemia, or Vitamin B12 Deficiency.

High RDW and Low MCV may indicate an Iron Deficiency

High RDW and Normal MCV  May indicate the supply of Vitamin B12 is insufficient, or the body is low in Iron.

Low RDW usually means Red Cells are consistent in size. Which is desirable. It is often not of any concern, or of any clinical significance.  Though that doesn’t necessarily mean all things are good.

A low reading that might raise attention, if other physical factors are impacting a patient, would be something lower than 10.2%

A low RDW can be caused by various medical conditions, or even be a normal characteristic of a given patient.

Some conditions that have to be tested for or eliminated when RDW is low, or even normal, may be:

Microcytic Anemia
Iron Deficiency Anemia
Vitamin B6 Deficiency
Vitamin B12 Deficiency