All lab markers

Blood count

RDW

How mixed your red-cell sizes are. Rising width is often the first sign of a developing deficiency. Higher results are the ones to watch. A common adult reference interval is 11–15 %.

Typical adult range

Reference interval
11–15 %
Often-cited tighter window
11.5–13.5 %

Red-cell size variation; rising = early deficiency. Your own lab's printed range is the one that applies to your result.

In more detail

Rising width = mixed cell populations, often early iron deficit.

What commonly moves it

  • Iron deficiencyLow stores or poor delivery limit red-cell production and thyroid conversion.
  • B12

These are commonly described physiological relationships, shared for education. They are not a diagnosis and cannot account for your medications, history, or symptoms — discuss your results with a licensed clinician.

Watching RDW over time?

Dose Compass charts each draw, flags meaningful moves, and helps you prepare questions for your clinician.

Start tracking