Red Cell Distribution Width (RDW) reflects the variability in RBC size (anisocytosis).

RDW-CV is calculated as the coefficient of variation of RBC volume, expressed as a percentage.

Clinical uses include:

Differentiating iron deficiency anemia from thalassemia trait.

Supporting diagnosis of megaloblastic anemia (vitamin B12 or folate deficiency).

Identifying mixed anemia conditions.

Monitoring treatment response in anemia patients.

The test is performed as part of a Complete Blood Count (CBC) using automated hematology analyzers.

Analyte: Variation in red blood cell size (RBC volume distribution).

Normal Range: ~11.5 – 14.5% (varies slightly by lab).

Abnormal Findings:

High RDW-CV: Suggests anisocytosis, commonly seen in iron deficiency anemia, megaloblastic anemia, or mixed anemia.

Normal RDW-CV with anemia: May suggest thalassemia trait or anemia of chronic disease.

Clinical Use:

Provides a percentage measure of RBC size variability.

Helps distinguish between different types of anemia.

Guides further diagnostic evaluation and treatment planning.