VGM (Average Corpuscular Volume)

The VGM means mean blood volume. A VGM 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. Your cells need oxygen to grow, reproduce, and produce energy. If your red blood cells are too small or too large, it could be a sign of a blood disorder such as anemia, a lack of certain vitamins, or other medical conditions.

Other names: NFS with differential, Average Cell Volume, Average Cell Volume

An MCV blood test is often part of a complete blood count (NGC), a group of tests that measures the number and type of cells in your blood. It is used to check your overall health.

An MCV test may also be used with other tests to help diagnose or monitor certain blood disorders, including anemia. There are several types of anemia, and each type has a different effect on the size, shape, and/or quality of your red blood cells. A CVD test can help diagnose what type of anemia you have.

Your health care provider may request a complete blood count, which includes a CVD test, as part of your routine exam. You may also take the test if you have a chronic (continuously) condition that could lead to anemia or if you have symptoms of anemia, which may include:

• Shortness of Breath
• Weakness or fatigue
• Headaches
• Vertigo
• Arrhythmia (a problem with the rhythm or frequency of your heart beat)

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

There is very little risk in taking a blood test. You may feel a slight pain or bruise where the needle was inserted, but most symptoms go away quickly.

A CVD test alone cannot diagnose any disease. Your provider will use your CVD results, other test results, and 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:

• Some forms of anemia, including iron deficiency anemia, the most common form of anemia. This happens when you don't have enough iron in your body.
• Thalassemia, which is a group of hereditary blood disorders (transmitted by families). These disorders cause your body to produce fewer healthy red blood cells and less hemoglobin. This can cause severe anemia.

If Your Results Show That Your Red Blood Cells Are Larger Than Normal, it may be a sign of:

• Pernicious anemia, which can be caused by:
  • A lack of vitamin B12
  • A condition that affects your body's ability to use vitamin B12, such as certain autoimmune conditions, celiac disease, or Crohn's disease
• Anemia caused by a lack of folic acid
• Liver disease

It is also possible to have anemia with A normal MCV. This can happen if anemia is caused by conditions such as:

• Sudden blood loss
• Kidney failure
• Aplastic anemia (rare)

If your CVD levels aren't in the normal range, it doesn't always mean you have a medical condition that needs treatment. Your age, diet, activity level, medication, menstrual period, and other conditions may affect test results. Talk to your provider to understand what your results mean.

Learn more about lab tests, reference ranges, and understanding results.

If your provider thinks you may have anemia or another blood disorder, you may have additional red blood cell tests with a VGM. These tests may include a red blood cell count and hemoglobin measurements. Together, these tests are called red blood cell indices.

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