MCV stands for mean corpuscular volume, which is a value calculated during a routine blood test called a complete blood count (CBC) . The MCV blood test measures the average size of your red blood cells. Red blood cells carry oxygen from your lungs to every cell in your body, and having a large number of atypically large or atypically small red blood cells can indicate certain conditions. An MCV blood test is helpful in diagnosing anemia or other blood disorders.

During an MCV blood test, a doctor draws blood from a vein to collect a sample. The MCV is routinely performed by an automated machine on all CBCs. An MCV test alone cannot diagnose any disease, and your healthcare provider will use the results of your MCV, other test results, and your medical history to make a diagnosis. If your results show that your red blood cells are smaller than normal, it may be a sign of certain types of anemia, including iron-deficiency anemia, the most common type, or thalassemia, an uncommon genetic condition. If your results show that your red blood cells are larger than normal, it may be a sign of liver disease or a vitamin deficiency.