What is RDW in Blood Test?

Learn about RDW in blood tests and how it can provide valuable information about your health. Find out what high or low values may indicate and how it can impact your overall well-being.


When you get a blood test, you may see a number of abbreviations and terms that you may not be familiar with. One of these is RDW, which stands for Red Cell Distribution Width.

What is RDW?

RDW is a measure of the variation in red blood cell size or volume. It is often included as part of a complete blood count (CBC) test and can provide valuable information about your overall health.

Importance of RDW

RDW can help doctors diagnose and monitor a variety of medical conditions, including anemia, vitamin deficiencies, and chronic diseases. A high RDW value may indicate that your red blood cells are not uniform in size, which could be a sign of an underlying health issue.


For example, a high RDW value may be seen in patients with iron deficiency anemia, as the body tries to produce more red blood cells of different sizes to compensate for the lack of iron. On the other hand, a low RDW value may indicate a more consistent size of red blood cells, which could be a sign of a different type of anemia.

Case Studies

In a study of patients with heart failure, those with a higher RDW value were found to have a higher risk of mortality. This suggests that RDW can also be used as a prognostic marker for certain conditions.


A normal RDW value typically falls between 11.5% and 14.5%. Values outside of this range may warrant further investigation by your healthcare provider.


RDW is an important parameter to consider when interpreting your blood test results. It can provide valuable information about your red blood cells and overall health, helping your doctor make an accurate diagnosis and develop an appropriate treatment plan.

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