MCV (Mean Corpuscular Volume): measures the average size of your red blood cells. It helps your doctor understand the type of anemia or other red blood cell issues you might have. Normal MCV means your red blood cells are a healthy size. Low MCV (small cells) may suggest iron deficiency anemia or other conditions affecting red blood cell production. High MCV (large cells) may suggest vitamin B12 or folate deficiency, liver issues, or other causes affecting red blood cell formation.