Complete Blood Count (CBC)

Red Cell Distribution Width (RDW)

Normal range 11.5–14.5 %. Specimen: Whole blood (EDTA).

Also known as: red cell variation.

11.5–14.5 %Reference range

Reference range

Conventional%

11.514.5

Specimen	Whole blood (EDTA)
Conventional range	11.5–14.5 %
SI range	11.5–14.5 %
Conversion factor	×1 (conventional → SI)
Panel	Complete Blood Count (CBC)

Convert any Red Cell Distribution Width (RDW) result between units on the unit converter.

What is the normal range for Red Cell Distribution Width (RDW)?

The standard teaching reference range for Red Cell Distribution Width (RDW) is 11.5–14.5 %. This value is measured in whole blood (edta).

Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population — always use the range printed on the actual result.

Above the range

Common causes of a high Red Cell Distribution Width (RDW)

Early or mixed nutritional deficiency
Recent transfusion
Reticulocytosis after bleeding

At the bedside

Nursing considerations

A high RDW (anisocytosis) with low MCV points toward iron deficiency over thalassemia.
Rises early in evolving nutritional anemias.

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