RDW Test
How much your red blood cells vary in size. Elevations often appear early in nutritional deficiencies.
What is RDW?
How much your red blood cells vary in size. Elevations often appear early in nutritional deficiencies.
RDW Reference Range
These are the typical adult reference ranges used by major US labs. Your report will include the specific range used by the lab that processed your sample.
| Population | Range |
|---|---|
| age 18+ | 11.5 – 14.5 % |
Reference ranges are educational. Always interpret your result with the specific range printed on your lab report and discuss anything outside the range with a clinician.
What your RDW result may mean
Often reflects iron, B12, or folate deficiency, or recent blood loss.
Educational only — not a diagnosis. Many factors can influence a single result. Discuss anything that concerns you with a healthcare provider.
Sources
Related Blood Health biomarkers
Markers commonly tested alongside RDW.
Frequently asked
No. TestWell's licensed physician network reviews and approves your order — usually within minutes. You can place an order online without an in-person visit or a referral from your own doctor.
Ready to test your rdw?
Order in two minutes, get physician-approved, and visit a lab the same day. Starts at $21.99.