Question 1

Should I be worried about a high RDW?

Accepted Answer

A high RDW on its own is a clue, not a diagnosis. If the rest of your blood count is normal, your clinician may simply repeat it. If hemoglobin or MCV is also abnormal, the next step is usually tests for iron, vitamin B12 and folate.

Question 2

Can low iron cause a high RDW?

Accepted Answer

Yes. Iron deficiency is one of the most common causes. RDW often rises early, sometimes before hemoglobin falls, because new red cells made with too little iron are smaller than older ones.

Question 3

Can dehydration affect RDW?

Accepted Answer

Dehydration mainly affects concentration-based results such as hemoglobin and hematocrit. It does not usually change RDW in a meaningful way.

Question 4

How long does it take RDW to return to normal?

Accepted Answer

Red blood cells live about 120 days, so after the cause is treated RDW typically improves over two to four months as new, uniform cells replace older ones.