cbc · RDW · RDW-CV
Red Cell Distribution Width
How much the size of your red blood cells varies. A higher RDW means a wider mix of cell sizes, which can be an early hint of evolving iron, B12, or folate deficiency — often before other indices shift.
This page is general wellness education, not medical advice. Your own lab’s reference range and your clinician’s interpretation always take precedence.
Typical reference range
| Group | General range |
|---|---|
| Adults | 11.5 – 14.5 % |
Units: %. Ranges vary by lab and assay — read yours against the range printed on your own report.
What high Red Cell Distribution Width can mean
- Iron deficiency
- B12 or folate deficiency
- Mixed anemias
- Recent blood transfusion
What low Red Cell Distribution Width can mean
- Generally not clinically concerning