MCV (Mean Corpuscular Volume)

Red cell size — a clue to the cause of anaemia.

What it is

MCV measures the average size of red blood cells. Small cells (microcytic) suggest iron deficiency. Large cells (macrocytic) point toward B12 or folate deficiency. Normal-sized cells (normocytic) with low HGB often reflect anaemia of chronic disease.

Why it matters

When anaemia develops, MCV helps identify the cause — guiding whether to prioritise iron, B vitamins, or further investigation. Different chemotherapy drugs also affect MCV through different mechanisms.

How to test

Full blood count.

This information is for educational purposes only. Always discuss testing and interpretation of results with your care team.

Optimal range

Below 80 fL

microcytic — investigate iron

80–100 fL

normal

Above 100 fL

macrocytic — investigate B12/folate or drug effect

How often

Each blood count panel.