The short explanation
These numbers describe your red blood cells. MCV is the average size of each red cell, MCH is the average amount of haemoglobin in each cell, and RDW shows how much the cells vary in size. Low MCV and MCH mean your red cells are smaller and paler than usual. A high RDW means there is a mix of sizes. This pattern is commonly seen with iron deficiency, where the body cannot make full-sized, well-filled red cells. It can also be seen with thalassemia trait, though RDW is often normal there. Your doctor will look at these alongside your haemoglobin and may order iron studies to confirm the cause.
What depends on your situation
The parts of this that change from woman to woman. Uncertainty is stated, not hidden.
- Each lab has its own reference range, so compare with the range printed on your report.
- Even if your haemoglobin is still normal, small cells can be an early sign of falling iron.
- Heavy periods, a vegetarian diet and recent pregnancy are common reasons for iron deficiency in women.
What this answer cannot determine
The boundary of online education. These need a clinician who can see you.
- This cannot tell you the cause of your results. Only your doctor, with your history and further tests such as ferritin, can interpret them for you.
Questions for your clinician
Take these with you. You can add any of them to an appointment card.
- Is my haemoglobin also low?
- Do these results suggest iron deficiency or something else?
- Should I get ferritin or a thalassemia test?
- What should I do next?
When to seek help
Clinician-approved guidance for this topic. When in doubt, being seen is never the wrong choice.
Book an appointment soon
- See a doctor within a few days if you are breathless, dizzy or very tired.
Raise it at a routine appointment
- Show the report to a doctor at a routine visit to discuss the next tests.
Sources
The evidence this explanation is built on.
- Hemoglobin test MedlinePlus (US National Library of Medicine)
- Anemia MedlinePlus (US National Library of Medicine)
- Iron deficiency anaemia NHS
Who wrote and reviewed this
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- Author
- AskHer Editorial (AI-assisted draft) AskHer's editorial team — not an individual clinician Works in English, தமிழ், हिन्दी
- Clinical reviewer
- Nobody yet No clinician has signed this answer off, and no person on the editorial team has read it yet. That is what the “Written with AI assistance” label means. It is queued for an editor to read, and then for a clinician who works in this area. The sources it was drafted against are listed above.
- Review status
- Written with AI assistance — not yet reviewed by a person
- Last reviewed
- Not yet reviewed by a person
- Version
- 1
Correction history
Substantive changes are listed, not quietly edited away.
No corrections have been made since this answer was first published.
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