MCV (mean corpuscular volume) reflects the average size of your red blood cells. This is important to measure, as it can indicate how much oxygen your cells are likely to be transporting around the body.
What might a low result mean?
Low MCV levels indicate that your red blood cells are a smaller size than they should be. This indicates that you may have microcytic anaemia, which is generally caused by iron deficiency anaemia. Low levels of iron in the blood reduce the amount of haemoglobin which can be made, thereby decreasing red blood cell size.
Iron deficiency anaemia may be caused by a reduced dietary intake of iron, or by malabsorptive conditions such as Crohn's disease, where the digestive tract is too inflamed to uptake enough iron.
What might a high result mean?
Elevated MCV levels indicate that your red blood cells are larger in size than they should be. This indicates a type of anaemia called macrocytic anaemia. This can be caused by a vitamin B12 or folate deficiency, and is often seen in cases of excessive alcohol consumption associated with liver inflammation.
Elevated MCV levels may also be seen in some people with hypothyroidism.