MCV (Mean Corpuscular Volume)


Mean Corpuscular Volume (MCV)

Mean corpuscular volume (MCV) is a type of blood test used to measure the size of red blood cells. The MCV measures the average size of a red blood cell (in femtoliter, fL). The result of the test is important in helping to diagnose certain types of anemia.

Preparation for a Mean Corpuscular Volume (MCV) Test

No special preparation is necessary for an MCV blood test; however, a physician may request that you fast for a few hours prior to the test, or discontinue medications that might affect the results.

Procedure for a Mean Corpuscular Volume (MCV) Test

A sample of the patient's blood is taken and sent to a lab. The test is done on a sample of the patient's whole blood, not just on plasma or serum. The lab tests the size of red blood cells in the sample and gives the MCV test result in femtoliter (fL).

Types of Anemia Associated With Low Mean Corpuscular Volume (MCV)

  • Megaloblastic Anemia – This is caused by vitiam B12 or folate deficiency.
  • Sickle Cell Anemia – This is caused by a genetic abnormaliy in hemoglobin.
  • Thalassemias – This is a group of inherited disorders of hemoglobin.
  • Myelodysplasia – This is a group of diseases where the body produces too few blood cells.
  • Erythropoietic Protoporphyria – This is an abnormality in one of the enzymes used in red blood cell production.

Risks of a Mean Corpuscular Volume (MCV) Test

  • Infection at the injection site.
  • Bleeding at the injection site.
  • Reaction to the contrast dye used in vein imaging.
  • Allergic reaction to the laboratory chemicals used in the test.
  • Thrombocytopenia (low platelet count) in patients with preexisting thrombocytopenia.

Why is a Mean Corpuscular Volume (MCV) Test Needed?

An MCV test is usually done when a doctor suspects that a patient has anemia. Anemia is a condition where the body does not have enough healthy red blood cells to carry oxygen throughout the body. The MCV test is useful in helping the doctor diagnose the type of anemia a person may have.

When is a Mean Corpuscular Volume (MCV) Test Performed?

While an MCV test is generally done if anemia is suspected, it can also be done as part of a complete blood count (CBC) to screen for certain conditions. It is also used to help diagnose problems with red blood cells, such as sickle cell anemia and thalassemia.