MCV Blood Test: What High and Low Levels Mean

A mean corpuscular volume (MCV) blood test measures the size of red blood cells. This test is part of a group of tests called red blood cell indices, which measure the quality of your red blood cells. An MCV that is too high or too low can indicate a certain type of anemia.

This article describes the MCV test, reviews the expected MCV range, and explains low and high MCV.

MCV is a measurement of the average size and volume of your red blood cells. An MCV that is too low or too high may indicate a type of anemia.

The MCV test is part of a group of tests called the red blood cell indices. These are used to help diagnose anemia.

The other tests in the red blood cell indices are:

• mean corpuscular hemoglobin
• mean corpuscular hemoglobin concentration
• red cell distribution width

An MCV blood test is part of a complete blood count. Doctors usually order a complete blood count as part of a routine annual physical examination. They may also want to check MCV if you are showing signs of anemia.

Signs of anemia include:

• cold hands and feet
• fatigue
• pale skin
• rapid heart rate
• shortness of breath
• weakness

The expected range of MCV is 80–100 femtoliter Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source . If your MCV level is outside this range, your doctor may want to repeat the test to confirm the result. Instead of repeating the test, your doctor may order additional blood work.

If you are experiencing symptoms of anemia, let your doctor know. Your doctor can check your MCV level and order any other tests.

Low MCV may indicate that you have microcytic anemia, meaning your red blood cells are small in size. Iron deficiency anemia is the most common cause of this type of anemia.

The blood loss from heavy menstruation can lead to iron deficiency anemia.

Other causes of microcytic anemia include:

• anemia of chronic diseases
• thalassemia, an inherited blood condition
• lead poisoning
• sideroblastic anemia, when bone marrow does not produce red blood cells properly
• myelodysplastic disorders involving incorrectly formed blood cells

A high MCV may indicate that you have macrocytic anemia, meaning your red blood cells are large in size. Common causes of macrocytic anemia include:

• folate deficiency
• vitamin B12 deficiency
• chemotherapy
• liver disease
• long-term alcohol misuse

Low vitamin B12 levels may occur in people eating strict vegan diets. People with inflammatory bowel disease or who have had gastrointestinal surgery have trouble absorbing nutrients in their gastrointestinal tract. This leads to low vitamin B12 levels.

Certain factors can affect MCV, making it unusually low or high. One study Trusted Source PubMed Central Highly respected database from the National Institutes of Health Go to source finds that MCV was elevated in people who smoke compared with people who do not. People who smoke have a compromised lung capacity.

Certain medications, such as proton pump inhibitors, metformin, and methotrexate, can cause impaired vitamin B12 and folate absorption. This leads to high MCV.

An MCV test requires a small sample of blood from your arm. There is no special preparation for the MCV test. If you are having blood drawn for other lab work, your doctor may ask you to fast for at least 8 hours before the test.

A lab technician or phlebotomist will collect a sample of blood using a small needle inserted into a vein in your arm. The blood sample goes to a lab for testing.

The MCV test involves minimal discomfort. You may feel a small pinching sensation when the needle is inserted. You may experience a small amount of bleeding or bruising.

Results of the MCV blood test should be available in 24–48 hours.

An MCV blood test is part of a group of tests that help doctors diagnose certain types of anemia. MCV is a measurement of the average size of red blood cells.

Your doctor may check your MCV level as part of your routine annual exam or if you have signs of anemia. A low MCV indicates microcytic anemia. A high MCV indicates macrocytic anemia.

Certain factors, such as smoking tobacco and taking certain medications, can increase MCV.