Mean corpuscular volumeMCV

Mean corpuscular volume (MCV) is the average size of your red blood cells. It is reported automatically as part of the full blood count and sorts anaemias into useful categories by whether the cells are small, normal or large.

It matters because cell size points toward causes: unusually small red cells often suggest iron deficiency, while unusually large ones can point to low B12 or folate, or to alcohol. MCV also feeds into blood-based biological-age scores.

In practice, MCV is read together with markers like ferritin, B12 and folate to pin down why the cells are the size they are, rather than interpreted on its own.