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Assess Red Cell Distribution Width - a measure of variation in red blood cell size
Normal range: 11.5-14.5%
Enter MCV for clinical context
RDW measures how much your red blood cells vary in size. Higher values indicate greater variation (anisocytosis), which helps differentiate causes of anemia.
| MCV / RDW | Normal RDW | High RDW |
|---|---|---|
| Microcytic | Thalassemia trait | Iron deficiency |
| Normocytic | Chronic disease | Mixed deficiency |
| Macrocytic | Aplastic, liver dz | B12/folate def. |
Red Cell Distribution Width (RDW) measures the variation in size of your red blood cells. It's calculated as the standard deviation of red cell volume divided by MCV, expressed as a percentage.
A normal RDW means red cells are relatively uniform in size. An elevated RDW (anisocytosis) indicates significant variation in cell size, which is useful for differentiating types of anemia and monitoring treatment response.