MCV Blood Test Value: What's Normal, High, or Low (2025)

• Introduction
  • What is MCV? Normal, high, and low
• Symptoms
  • What are the symptoms of high MCV?
• Diagnosis
  • What does an MCV test tell you?
• MCV in Children
  • What is a normal MCV in children?
• FAQs
  • Frequently asked questions (FAQs) about MCV blood test high levels

What is MCV? Normal, high, and low

The mean corpuscular volume (MCV) measures the average size of the red blood cells. The average MCV ranges from 80 to 100 femtoliters.

MCV can be high, low, or normal:

• Microcytic (micro=small): MCV level less than 80 fL
• Normocytic: MCV level between 80 and 100 fL
• Macrocytic (Micro=large): MCV level greater100 fL

The MCV level is measured as part of a hemogram or complete blood count (CBC) blood test. The test reports the red blood cell count (RBC), white blood cell count (WBC), and platelets. The size of the red blood cells is included as well.

When anemia is present (low RBC), MCV is helpful in diagnosing the cause.

Microcytic anemia is usually due to low iron. Each red blood cell contains hemoglobin which helps transport oxygen in the body. When there are inadequate iron stores in the body, less hemoglobin is made, and each red blood cell is smaller because it contains less hemoglobin.

Macrocytic anemia (high MCV) is most often due to decreased levels of vitamin B12 or folate in the body. Normally, red blood cells are shaped as biconcave discs, like the shape you get when you squeeze a marshmallow. B12 and folate are important building blocks of the RBC wall membrane. If their levels are decreased, there are fewer materials available to build those membranes, and it turns out that the surface area and the amount of membrane to contain the inside of the RBC is less when the cell is more round instead of concave. That makes the RBC appear larger, and that leads to a higher MCV.

What are the symptoms of high MCV?

High MCV in itself will not cause any symptoms. It can be associated with anemia if the red blood cell levels decrease and the oxygen delivery to tissues is decreased. If the elevated MCV is due to vitamin B12 deficiency, there can be symptoms associated with pernicious anemia (the term to describe low B12).

Common symptoms of anemia may include:

• Fatigue
• Weakness
• Light-headedness or dizziness
• Palpitations
• High heart rate (tachycardia)
• Chest pain
• Abnormal heart rhythm (arrhythmia)
• Shortness of breath
• Fainting episodes
• Pale skin and mucous membranes

What does an MCV test tell you?

An MCV measures the size of a red blood cell. Microcytic (small) red blood cells often are due to iron deficiency. Macrocytic (large) red blood cells are most often due to Vitamin B12 and/or folate (folic acid) deficiency).

The CBC test may also detect abnormalities of white blood cells or platelets.

What else does MCV diagnose?

Most commonly, the MCV is useful in the diagnosis of the type of anemia present.

MCV may have other uses, such as:

• High MCV may signify a poorer prognosis in patients with esophageal cancer.
• High MCV may suggest a poorer prognosis in patients with chronic kidney disease, regardless of whether they are on dialysis.
• High MCV is associated with a poorer prognosis and increased recurrence of rectal cancer.
• High MCV in older adults may be associated with poor cognitive function and an increased risk of dementia.

What is a normal MCV in children?

MCV measures the average size of red blood cells (RBCs). The normal MCV range in adults is from 80-100 fL.

Normal pediatric ranges are shown in the table below.

What causes low MCV in children?

A low MCV blood test result indicates that the average RBC size is smaller than normal, which could be due to:

• Iron deficiency anemia
• Thalassemia (a hereditary hemolytic disease caused by faulty hemoglobin production)
• Sideroblastic anemia (failure to use iron properly in RBC production)
• Lead poisoning
• In copper poisoning, the MCV may be high, low, or normal

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What causes high MCV in children?

High MCV may be associated with the following:

• Vitamin B12 deficiency
• Folate deficiency
• Liver Disease
• Hypothyroidism
• Medications like antiseizure medicines and immunosuppressants
• Aplastic anemia is a failure of the bone marrow to produce all types of blood cells including red blood cells, white blood cells, and platelets
• Myelodysplastic syndrome, where blood cells do not mature properly
• Chronic hypoxia or low oxygen levels in the blood
• Benign Familial Macrocytosis, an inherited disease
• Leukemia
• Congenital Heart Disease
• Down Syndrome
• Reticulocytosis or immature red blood cells that are larger than red blood cells that have fully developed
• Alcohol Abuse
• Diamond-Blackfan Anemia

What causes anemia in children?

Causes of anemia in children vary depending on their age, gender, and ethnicity:

• Birth to 3 months:
  • Physiological anemia, which is a normal developmental response to increased tissue oxygenation
  • Pathologic anemia or anemia due to a disease or illness may be due to causes like:
    • Blood loss
    • Hemolytic disease (Rh or ABO incompatibility)
    • Glucose-6-phosphate dehydrogenase deficiency
  • Congenital infections (infections in the womb or during childbirth
  • Twin-twin transfusion
• 3-6 months:
  • Hemoglobinopathy (abnormal hemoglobin production)
• Children and adolescents:
  • Cow's milk intake
  • Menarche in female children (the start of menses)

Frequently asked questions (FAQs) about MCV blood test high levels

What does a high MCV blood test mean?

A high MCV blood test result means that the average size of your red blood cells (RBC) is larger than normal. MCV is a test that is part of a complete blood count (CBC) or hemogram and may be used to help identify the cause of anemia.

What are the common causes of high MCV?

Some of the common causes of high MCV include:

• Low vitamin B12 levels
• Low folate (folic acid) levels
• Gastrointestinal conditions that prevent vitamin absorption such as:
  • Diphyllobothrium latum infection
  • Celiac disease
  • Inflammatory bowel disease
  • Surgical removal of sections of the intestines
• Liver disease
• Alcohol abuse
• Hypothyroidism
• Carbon monoxide poisoning
• Aplastic anemia (a condition where the bone marrow fails to make red blood cells)
• Hemolytic anemias (conditions where RBCs are prematurely destroyed)
• Cold agglutinin disease (a condition where the body's immune system attacks your red blood cells and destroys them)
• Chronic hypoxia (low oxygen levels in the blood and the body tissues)
• Benign familial macrocytosis (high MCV level due to a genetic defect)
• Myelodysplastic syndrome (a group of disorders caused when something disrupts the production of blood cells)
• Certain medications including chemotherapy agents and antiseizure medications

Is a high MCV serious?

A high MCV needs to be interpreted along with RBC levels in the bloodstream. The seriousness depends upon the underlying cause.

Can vitamin deficiencies cause high MCV?

Vitamin B12 or B9 (folate, folic acid) deficiencies may cause a high MCV. Vitamin B12 and folate deficiencies may be due to poor diet intake or from gastrointestinal conditions that prevent absorption of these vitamins. These include pernicious anemia, inflammatory bowel diseases, celiac disease, gastritis, and certain gastro-intestinal surgeries.

How is high MCV treated?

Treatment for high MCV will depend on the underlying cause. Vitamin deficiencies may be treated with appropriate supplementation and a nutritious diet. If the underlying cause is identified, it will need to be treated to prevent recurrence of the vitamin deficiency.

What is the difference between high MCV and low MCV?

A normal MCV measures the size of the red blood cell and is between 80 fL and 100 fL. High MCV is a red blood cell that is larger than normal and measures greater than 100 fL. Low MCV means that the red blood cell is smaller and measures less than 80fL.

The most common cause for a high MCV, or macrocytic anemia, is vitamin B12 or folate (folic acid) deficiency. MCV (microcytic anemia) is most often related to iron deficient conditions.

What other blood tests are done with an MCV test?

A mean corpuscular volume (MCV) test is a part of a complete blood count test which analyzes all the blood cells. MCV is one of the indices pertaining to red blood cells and refers to their average size.

Other tests done with an MCV test include:

Red blood cell (RBC):

• RBC count: The number of cells per microliter of blood
  • Red cell distribution width (RDW): The percentage of variation in RBC sizes
  • Mean corpuscular hemoglobin (MCH): The amount of hemoglobin in a red cell
  • Mean corpuscular hemoglobin concentration (MCHC): The average percentage of hemoglobin concentration in a given volume of RBCs
  • Hemoglobin: The amount of hemoglobin in a microliter of blood
  • Hematocrit: The percentage of red blood cells in the blood
• Platelet count, and mean platelet volume (MPV) which is the average platelet size
• White blood cell (WBC) count, total number of each type of WBC

What is macrocytic anemia and how is it related to MCV?

Macrocytic anemia is a type of anemia in which the red blood cells are abnormally large. Mean corpuscular volume (MCV) is a blood test that measures the average size of red blood cells, and if a person has anemia and the MCV is higher than normal, they are considered to have macrocytic anemia.

Does a high MCV mean I have a blood disorder?

A high MCV may or may not be associated with a blood disorder. It may be a consequence of poor diet, an underlying illness, or a potential blood disorder.

When should I see a doctor about a high MCV?

You will be aware that your MCV is high because of a blood test (CBC, hemogram) that was ordered by a healthcare provider, and they should discuss that result and its importance and significance with you.

The importance of the high MCV depends upon the clinical situation and any other medical problems that may also be present.

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Koury MJ, Hausrath DJ. Macrocytic anemias. Curr Opin Hematol. 2024 May 1;31(3):82-88.

Koury MJ. Abnormal erythropoiesis and the pathophysiology of chronic anemia. Blood Rev. 2014 Mar;28(2):49-66.