MCV (Mean Corpuscular Volume)
MCV is the average size of a red blood cell. It is one of the most useful single values on a CBC because it classifies anaemia by cause: microcytic (small cells), normocytic (normal size), or macrocytic (large cells).
Normal Range
80–100 fL
Reference ranges may vary slightly between laboratories. Always interpret your result in context with your doctor.
Why is MCV measured?
MCV is automatically calculated on every CBC. It is used to investigate the cause of anaemia and to monitor responses to treatment. The pattern (microcytic, normocytic, macrocytic) directs the next investigations.
High MCV means…
High MCV (macrocytosis) typically indicates B12 or folate deficiency, alcohol use, hypothyroidism, liver disease, or certain medications. Macrocytic anaemia from B12 deficiency is also called megaloblastic.
Low MCV means…
Low MCV (microcytosis) typically indicates iron deficiency, thalassaemia, anaemia of chronic disease, or lead poisoning. The most common cause globally is iron deficiency.
Symptoms associated with abnormal MCV
When MCV is high:
- Symptoms of underlying anaemia: fatigue, breathlessness
- Sore tongue (B12 deficiency)
- Numbness in feet (B12 deficiency)
- Cognitive slowing
When MCV is low:
- Fatigue, pallor (iron deficiency)
- Hair loss
- Brittle nails
- Cold extremities
How to improve your MCV
- If MCV is low, check ferritin first — iron deficiency is the leading cause.
- If MCV is high, check B12 and folate, and review alcohol intake.
- Microcytosis with normal ferritin and CRP raises suspicion for thalassaemia trait — common in South Asian, Mediterranean, African populations.
Frequently asked questions about MCV
What MCV is associated with thalassaemia?
Thalassaemia trait usually causes microcytosis (MCV 60–75 fL) with normal or only mildly low haemoglobin and normal ferritin. Iron supplementation does not correct thalassaemia and should be avoided unless iron deficiency is also confirmed.
Can alcohol raise MCV?
Yes — alcohol is the second most common cause of macrocytosis. Chronic heavy drinking causes MCV to rise within months and often normalises within 3 months of abstinence.
Medical Sources
This page is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider about your individual results.