RDW
A measure of how variable your red blood cell sizes are.
What is it
RDW measures the variation in red blood cell size. Elevation has been associated with various conditions in research literature, beyond just anemia.
Why it's measured
RDW has been studied as a marker not just of anemia but of inflammation, mortality risk, and certain chronic conditions in published research.
Reference range
Standard laboratory reference
11.5 – 14.5 %
Reference ranges vary by laboratory. Your individual reference range will appear on your test report and should be interpreted by your physician in the context of your overall health profile.
Where does your number land?
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Drag to your own RDW · RBC Distribution Width result.
Educational only, not a diagnosis. Ranges vary by laboratory. See which panel includes RDW · RBC Distribution Width.
What results may indicate
Elevated
Has been associated with various anemias, inflammation, and elevated mortality risk in published research.
Lower
Generally considered favorable.
These associations are general. They are not a personal diagnosis or prediction. Discuss your individual results with your physician in the context of your full health profile.
When it's measured
Part of standard CBC.
Related markers
Common questions
RDW measures the variation in red blood cell size. Elevation has been associated with various conditions in research literature, beyond just anemia.
It's one of the markers used to build a fuller picture of your health. On its own it tells you very little, so it's most informative when reviewed alongside related markers.
It's measured from a standard blood draw at Quest or LabCorp. RDW \u00b7 RBC Distribution Width is one of the markers included in the OPTML Apex Panel, where your results are read across systems and reviewed by a U.S.-licensed physician.
Reference ranges vary by laboratory, and a single value rarely tells the whole story. Review your result with a physician in the context of your other markers, symptoms, and history.
RDW \u00b7 RBC Distribution Width is one signal among many. Answer a few quick questions and we’ll point you to the panel that fits.
Measured in
A complete look at your heart, hormones, metabolism, inflammation, and longevity systems — drawn at Quest or LabCorp, reviewed by a U.S.-licensed physician.
Find the right panel →This information is for general educational purposes only and is not medical advice. Lab results alone are not intended to diagnose, treat, or cure any condition and do not replace the advice of a healthcare provider. OPTML does not offer medical advice, a diagnosis, medical treatment, or any form of medical opinion.
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