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What Does It Mean If Your MCV Blood Test Is High?

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When your mean corpuscular volume (MCV) blood test shows high levels, it means that your red blood cells (RBC) are unusually large and that it interferes with blood functions. You can take the CBC test, inclusive of MCV labs to help diagnose conditions related to RBC physical changes. Find out more about this test as you read further down. 

What Is an MCV Blood Test?

An MCV blood test measures the size of your RBC to help diagnose anemia, folate deficiency, liver disease, hypothyroidism, and chronic hypoxia. 

RBCs are responsible for supplying oxygen to cells and collecting wastes like carbon dioxide for removal. A change in their average size affects this process, making it an effective indicator of anemia and related diseases. 

Your doctor may order this blood test to be taken during your wellness checkup as part of the complete blood count (CBC). But often, it’s a response to verify symptoms of the conditions as mentioned above. 

The MCV blood test is often performed together with other tests that determine the characteristics of RBC, such as the following:

  • Mean corpuscular hemoglobin (MCH): measures the average amount of hemoglobin (the protein that carries oxygen) in the RBC. 
  • Mean corpuscular hemoglobin concentration (MCHC): screens for the concentration level of hemoglobin in a RBC. 
  • Red cell distribution width (RDW): compares the sizes of RBCs and determines significant differences. 

By looking into all these indices, doctors can diagnose different types of anemia and other health conditions influencing hemoglobin production and RBC size. 

When Should You Take the MCV Blood Test?

Doctors often recommend the MCV blood test when symptoms of anemia, specifically macrocytic and microcytic anemia, appear. These symptoms include:

  • Shortness of breath
  • Fatigue or weakness 
  • Irregular heartbeat (arrhythmia)
  • Numbness and tingling in the extremities 
  • Trouble concentrating
  • Appetite loss
  • Irritability

Macrocytic anemia is a blood disorder characterized by abnormally large RBCs, while microcytic anemia occurs when the RBCs are smaller than the average size. Both conditions entail low hemoglobin.

How Is the Test Done?

An MCV blood test requires a blood sample drawn from the veins. That’s why it has to be performed in a trusted laboratory. No special preparation is necessary, especially if it’s part of a CBC test. But your doctor may request you to fast for 8 hours depending on the test’s purpose. 

Pro Tip: The CBC test includes an MCV blood test. You can order it online here at Personalabs and get tested at one of our partner centers. Then the test results will be sent confidentially through your account, which you can print up and show your doctor.

What Does It Mean To Have High MCV Levels?

Getting a high MCV level (above 100 fl) in your blood test suggests macrocytic anemia and indicates that you have larger than normal RBCs. The normal MCV blood test range is from 80 to 100 femtoliters (fl).  

Having high MCV levels can be due to the following reasons:

Vitamin B12 or B9 Deficiency

Lack of vitamin B12 (cobalamin) and vitamin B9 (folate) cause deformities and size disparity in the RBCs. After all, both vitamins are involved in the production of red blood cells in the bone marrow. In that sense, if you have high MCV levels, it may be time to increase your uptake of foods rich in vitamins B12 and B9 or include supplementation as advised by your healthcare provider.

Autoimmune Gastritis

Autoimmune gastritis is a chronic disease characterized by the inflammation of the stomach’s body and fundus which is the upper section. The development of this condition leads to folate deficiency which, as mentioned above, causes macrocytic anemia. 


Thyroid hormones stimulate the production of RBCs. So those with hypothyroidism (an inactive thyroid gland)are at risk of anemia based on multiple RBC indices including its irregular size due to abnormal maturation. 

Liver Disease

Liver disease can change the structure and composition of your RBCs. For example, if you have liver disease, you’re most likely to have increased cholesterol deposition in your RBCs that alters cell size.

Chronic Alcoholism

Alcohol abuse impedes bone marrow function, the site of red blood cells production. As a result, RBCs can be low in count or are unusually large which elevates your MCV level. 


Drugs that interrupt folate absorption contribute to macrocytic anemia. These include chemotherapy drugs, antiretroviral medications, and antiseizure drugs.   

What Is the Treatment for High MCV?

The right treatment for high MCV should respond to the exact cause of the condition. For example, if it’s folate deficiency, dietary adjustments and supplementation can suffice. The same goes for chronic alcoholism. On the other hand, if the elevated MCV is due to an underlying disease, your doctor will prepare a treatment plan specific to the health condition. 

Other Frequently Asked Questions

What Cancers Cause High MCV Levels?

Liver cancer is the most associated type of cancer with high MCV levels since liver dysfunctions lead to more fats adhering to the membrane of the red blood cells, increasing their surface levels. Other cancers could also lead to macrocytic anemia such as colorectal and esophageal cancers.  

What Is the Most Common Cause of High MCV?

Folate deficiency remains the most common factor for high MCV. Even the associated diseases to elevated MCV links to the malabsorption of vitamin B12 and B9. In that sense, you can avoid having high MCV in your blood test when you ensure the inclusion of the said vitamins in your diet. 

How Long Does It Take for MCV To Return to Normal?

When the proper treatment is set, you can expect to have your high MCV levels fixed within 2 to 4 months. For example, if you withdrew from alcohol consumption and increased your dietary intake of folate-rich foods, your bone marrow will produce normal sized RBCs provided that there are no other factors for the condition. 

The Bottom Line

The CBC test provides information about your blood including your red blood cell structure and count. As it often includes the MCV test, it’s best to understand the results and what it means for your health to have high MCV levels. If you indeed have elevated MCV in your blood test, other lab assessments can also be ordered such as an iron panel blood test and a vitamin b12 blood test to diagnose anemia.

Medically Approved By Dr. Edward Salko, MD

Dr. Edward Salko is the board-certified physician who reviews lab tests provided by PERSONALABS™. He earned his Bachelor of Science in chemistry and pre-med from the University of Florida in Gainesville and his Doctor of Osteopathy Medicine in 1980 from Kansas City University School of Medicine.

Dr. Salko’s career has specialized in family and emergency medicine. His passion is to provide clients with the tools they need in the most convenient way possible to allow them to take charge of their own healthcare. He has held a variety of positions in Kansas, Florida and Washington. Currently, in addition to his duties as Medical Director for Personalabs, he is a practicing emergency physician in Kennewick, Washington.

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