Biomarker education

RDW: What It Measures & Why People Track It

Also called: Red cell distribution width

RDW describes how much variation there is in the size of red blood cells.

General biomarker education — not personalized medical advice. Learn more

Result on your report

Illustrative

RDW

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Range: Low – High

LowReference intervalHigh

What it generally measures

This CBC value reflects the spread, not the average, of red blood cell sizes in your sample.

Common units on reports: %

RDW is typically reviewed alongside MCV and the other CBC values as a combined pattern.

Changes over time do not by themselves establish a diagnosis. Learn more

Questions to bring

Illustrative

Ask how RDW is being considered alongside MCV and the other red cell indices for you.

Organize your own lab history

Part of Kind Panel education · Lab results guide

Reference range

RDW reference range

What the range on your report means for this marker.

Panel guide

Related panel guide

Understand the broader panel this marker appears on.

Related biomarker

MCV

MCV describes the average size of red blood cells and is one of the CBC red-cell indices.