MCV Lab Results Explained: Normal Range & High or Low MCV
Also known as: Mean corpuscular volume, MCV blood test
MCV (mean corpuscular volume) measures the average size of your red blood cells and is one of the most useful numbers for classifying anemia. It's reported on a complete blood count (CBC). A normal MCV is roughly 80–100 femtoliters (fL); a low MCV means small cells (often iron deficiency), while a high MCV means large cells (often B12 or folate deficiency).
MCV normal range
| Category | Range (fL) |
|---|---|
| Normal | 80–100 fL |
| Low (microcytic) | < 80 fLSmall red cells |
| High (macrocytic) | > 100 fLLarge red cells |
Reference ranges vary by laboratory. Use the range printed on your own report as the definitive comparison.
What high MCV can mean
- Vitamin B12 or folate deficiency
- Alcohol use
- Liver disease
- Hypothyroidism
- Certain medications
What low MCV can mean
- Iron-deficiency anemia (the most common cause)
- Thalassemia
- Chronic disease
What to do about an abnormal result
- MCV points your doctor toward the likely cause of anemia and which follow-up tests to run.
- Low MCV → iron studies; high MCV → B12, folate, and sometimes thyroid tests.
- Interpret with hemoglobin, MCH, MCHC, and the red-cell distribution width (RDW).
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Frequently asked questions
What does a high MCV mean?
A high MCV (macrocytosis) means your red blood cells are larger than normal. The most common causes are vitamin B12 and folate deficiency, alcohol use, and liver disease. It's followed up with B12/folate testing and a review of medications and alcohol intake.
What does a low MCV indicate?
A low MCV (microcytosis) means small red blood cells, most often from iron-deficiency anemia or thalassemia. Iron studies, including ferritin, are the usual next step to find the cause.
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Medically reviewed by Antonieta Rueda, MD and Ayham Shneker, MD · Last reviewed July 6, 2026
This article is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or your lab results.