RDW 15.2% — what does it mean?

What this test is

How much your red blood cells vary in size.

What your number means

Under 12.8% is where you want to sit. Around 13% is the first gentle warning. By 14% the unevenness is real, and past 15% your blood factory is clearly straining. The step from 12.5% to 14% looks tiny written down, but it’s one of the biggest differences on this whole report.

Why it matters

Uniform red cells mean a calm, well-run blood factory; uneven cells are an early stress signal — and RDW is one of the strongest predictors of long-term health there is.

Think of your bone marrow stamping out red cells like coins. When the machine is healthy, every coin is the same size. When it’s tired or short on raw materials, the coins come out in mixed sizes — that spread is RDW.

What to do about it

A raised number is usually a fuel problem, so check iron, B12 and folate first and correct whichever is low. Red cells take about three months to fully turn over, so retest after that rather than sooner.

Where it sits in your Body Age

RDW (Red Cell Distribution Width) is one of the tests behind Blood Renewal — How cleanly your body is building fresh blood cells, day after day. It is one of four areas that together give a single number: the age your body reads, next to the age on your birth certificate.