Mean corpuscular volume, or MCV, is a measurement of red blood cell size. A doctor usually requests an MCV test as part of a complete blood count, which analyzes many blood components, including white blood cells and platelets.

If a doctor suspects that a person has anemia, they will use an MCV test to confirm the type of anemia. Different MCV levels indicate specific types of anemia.

In this article, we examine what MCV levels measure. We also look at what different MCV levels mean and what may cause these changes.

Share on Pinterest
AzmanJaka/Getty Images

Red blood cells have many characteristics that a doctor can measure using specific indicators. MCV indicates the average red blood cell size and volume.

Other red blood cell indicators include:

  • Mean corpuscular hemoglobin (MCH): This is the average hemoglobin level within a red blood cell.
  • Mean corpuscular hemoglobin concentration (MCHC): This is the average hemoglobin concentration in red blood cells.
  • Red cell distribution width (RDW): This measures the variation in red blood cells’ size.

Doctors use these measurements when diagnosing specific types of anemia, as well as other health conditions.

Learn more about MCH levels in blood tests here.

A person does not need to prepare for an MCV blood test.

During an MCV blood test, a doctor draws blood from a vein to collect a sample. While the doctor is taking the blood sample, a person may feel a little pain and a stinging sensation.

Are there any risks?

Drawing blood carries few risks. However, everyone is different, and sometimes blood collection is more straightforward in some people than in others.

The side effects of an MCV blood test may include:

  • bruising
  • excessive bleeding
  • feeling lightheaded
  • infection

A doctor typically measures someone’s MCV levels if they are presenting with:

  • dry, cracked lips
  • cold intolerance
  • fatigue
  • bruising or bleeding easily
  • unexplained weight loss
  • cold hands and feet
  • looking paler than usual
  • jaundice

These symptoms indicate conditions that affect the size of red blood cells, making them smaller or larger than usual.

When red blood cells are smaller than expected, a person likely has microcytic anemia. If they are larger, a person may have macrocytic anemia.

A typical adult MCV level is 80–100 femtoliters (fl).

Specific levels for different ages and sexes include:

12–18 yearsAdults
Males88 fl90 fl
Females90 fl90 fl

Children aged 6–12 years tend to have an MCV of 86 fl.

MCV results may differ among labs, so people should not worry if their reading is slightly above or below these ranges.

When a person has an MCV level below 80 fl, this suggests they have microcytic anemia. Microcytic anemia is a type of anemia in which red blood cells are smaller than usual.

Iron deficiency causes microcytic anemia. A person usually develops an iron deficiency due to an underlying health condition or factors such as diet and medications.

Common causes

Iron deficiency causes include:

  • Blood loss: A person may experience bleeding from the gastrointestinal (GI) tract when they have colon cancer or take nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin. People with heavy periods may also lose a lot of iron through menstrual blood.
  • Diet: If someone eats a plant-based diet or an omnivorous diet low in iron, they may need to take iron supplements or focus on eating iron-rich foods.
  • Reduced iron absorption: Ulcerative colitis, Crohn’s disease, weight loss surgery, and Helicobacter pylori infection may all reduce the absorption of iron.
  • Pregnancy: During pregnancy, people may need to supplement their iron intake, as the body needs more iron to support fetal development.

Thalassemia

Thalassemia is a condition where the body does not make enough normal hemoglobin. It is a genetic condition that a person inherits from their parents.

Thalassemia can range from mild to severe. If a person has mild thalassemia, they may have mild anemia or not present with any signs or symptoms. If someone has severe thalassemia, they may require regular red blood cell transfusions.

If someone has a high MCV level, their red blood cells are larger than usual, and they have macrocytic anemia. Macrocytosis occurs in people with an MCV level higher than 100 fl.

Megaloblastic anemia is a type of macrocytic anemia. Deficiencies in cobalamin (vitamin B12) and folate (vitamin B9) are the most common causes of megaloblastic anemia.

Dietary and autoimmune factors

The following factors may cause vitamin B12 deficiency.

Vegan diet

Vitamin B12 deficiency may occur when following a vegan diet. This is because vitamin B12 naturally occurs in animal sources. A person can take vitamin B12 supplements or consume vitamin B12-fortified foods to alleviate symptoms.

Autoimmune gastritis

This is an inflammatory condition that affects the stomach, particularly the parietal cells that make intrinsic factor. If the parietal cells do not make enough intrinsic factor, vitamin B12 cannot get into the bloodstream via the distal small intestine. Doctors treat the deficiency with vitamin B12 injections and, sometimes, iron infusions.

Other causes

Other factors that may contribute to vitamin B12 and vitamin B9 deficiencies include:

  • breastfeeding or chestfeeding
  • consuming too much alcohol
  • tapeworm
  • Crohn’s disease
  • cancer treatment medications

If someone is frequently tired and feels cold all the time, they may have anemia. People experiencing symptoms of anemia should contact a doctor.

A doctor may ask about a person’s family’s medical history. Some conditions that cause anemia, such as thalassemia and Crohn’s disease, run in families.

An MCV test measures the size and volume of red blood cells. A normal MCV range is roughly 80–100 fl.

If someone’s MCV level is below 80 fl, they will likely develop or have microcytic anemia. Alternatively, if their MCV levels are greater than 100 fl, they could experience macrocytic anemia.

People with microcytic anemia may feel the cold more and look paler than usual. People with macrocytic anemia may experience jaundice.

If someone has symptoms of anemia, they should contact a doctor for advice. Usually, treating the underlying cause of the anemia alleviates symptoms.