What is Mean Platelet Volume (MPV)?

MPV is a Measurement of the Average Size of Platelets

Complete Blood Count (CBC). Credit: Javier Larrea / GettyImages

You may have seen the letters "MPV" as part of your Complete Blood Count (CBC) test, which is used in health screening tests, as well as monitoring treatment for many health conditions. The CBC test assesses your red blood cells (blood-forming cells), white blood cells (infection-fighting cells), and platelets (clot-forming cells). 

MPV (which stands for mean platelet volume) is a measure of the average size of platelets, which are cells that help your blood clot.

What Does the Mean Platelet Volume (MPV) Tell You About Your Health?

Platelets are the cells responsible for forming clots. They are essentially what keeps us from bleeding excessively when cut, and they help patch up any holes in blood vessels throughout the body.

Platelets are produced in the bone marrow by cells called megakaryocytes. The platelets themselves are just pieces of megakaryocytes, without nuclei, released into the bloodstream from the marrow. Usually, younger platelets are larger than older platelets.

What Does A High Mean Platelet Volume (MPV) Mean?

A high MPV is usually a sign that there are more young platelets circulating in your bloodstream. If you have had a procedure such as major surgery, your body is using up platelets to repair the cuts to the blood vessels. In response, your bone marrow releases more of the young, larger platelets, and your MPV rises

A high MPV with a low platelet count shows the bone marrow is actively producing platelets, but they have been or are being used up by some process in your body.

Your doctor will assess this in light of what conditions or procedures you have had, and do further tests if needed.

Conditions that may cause an elevated MPV include idiopathic thrombocytopenic purpura, which leads to an immune system-mediated destruction of platelets. An elevated MPV can also be seen in blood cancers, such as leukemia.

How High MPV Results Are Followed Up On

When the MPV value is high, the lab will usually check it with a differential blood smear. The technologist will make and stain a slide of your blood and look at it under the microscope to see if the platelets are clumping together or if you actually have giant platelets. 

The CBC test requires anticoagulated blood and is usually drawn in a purple top tube. Clumping platelets are probably due to the blood sample being clotted. This may require a repeat blood draw, and some people need their blood drawn in a different tube as their platelets still clump with the anticoagulant used in the purple top tube. 

That being said, some people truly have giant platelets, either from immune thrombocytopenic purpura (ITP) or Bernard-Soulier disease. 

What Does A Low Mean Platelet Volume (MPV) Mean?

A low MPV along with a low platelet count can point towards disorders affecting the bone marrow that slow down or decrease the production of platelets, such as a condition called aplastic anemia.

In addition, a low MPV can be seen with high, low or normal platelet counts in sepsis (a life-threatening reaction to infection in the body), splenomegaly (enlarged spleen), chronic kidney failure, or treatment with drugs that suppress blood production.

Sources:

American Association for Clinical Chemistry. Platelet Count

Leader A, Pereg D, Lishner M. Are platelet volume indices of clinical use? A multidisciplinary review. Ann Med. 2012 Dec;44(8):805-16.

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