MCV (Mean Corpuscular Volume)

What is an MCV blood test?

MCV stands for mean corpuscular volume. There are three main types of corpuscles (blood cells) in your blood–red blood cells, white blood cells, and platelets. An MCV blood test measures the average size of your red blood cells, also known as erythrocytes. Red blood cells move oxygen from your lungs to every cell in your body. Your cells need oxygen to grow, reproduce, and stay healthy. If your red blood cells are too small or too large, it could be a sign of a blood disorder such as anemia, a vitamin deficiency, or other medical condition.

Other names: CBC with differential

What is it used for?

An MCV blood test is often part of a complete blood count (CBC), a routine screening test that measures many different components of your blood, including red cells. It may also be used to diagnose or monitor certain blood disorders.

Why do I need an MCV blood test?

Your health care provider may have ordered a complete blood count, which includes an MCV test, as part of your regular checkup or if you have symptoms of a blood disorder. These symptoms include:

  • Fatigue
  • Unusual bleeding or bruising
  • Cold hands and feet
  • Pale skin

What happens during an MCV blood test?

During the test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

You don’t need any special preparations for an MCV blood test. If your health care provider has ordered more tests on your blood sample, you may need to fast (not eat or drink) for several hours before the test. Your health care provider will let you know if there are any special instructions to follow.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

If your results show that your red blood cells are smaller than normal, it may indicate:

  • Iron-deficiency anemia or other types of anemia
    • Anemia is a condition in which your blood has a lower than normal amount of red blood cells. Iron-deficiency anemia is the most common form of anemia.
  • Thalassemia, an inherited disease that can cause severe anemia

If your results show that your red blood cells are larger than normal, it may indicate:

  • A vitamin B12 deficiency
  • A deficiency in folic acid, another type of B vitamin
  • Liver disease
  • Hypothyroidism

If your MCV levels are not in the normal range, it doesn’t necessarily mean that you have a medical problem needing treatment. Diet, activity level, medicines, a women’s menstrual cycle, and other considerations can affect the results. Talk to your health care provider to learn what your results mean.

Is there anything else I need to know about an MCV blood test?

If your health care provider suspects you have anemia or another blood disorder, he or she may order additional tests of your red blood cells. These include a red blood cell count and measurements of hemoglobin.

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