Understanding Your MPV Blood Test Results

The mean platelet volume (MPV) blood test measures the average size of your platelets, the cells responsible for forming blood clots to slow blood loss, prevent infection, and promote healing.

A healthcare professional may want to check your MPV levels if you have symptoms of a bleeding or bone marrow disorder, such as prolonged bleeding or small red/purple spots on the skin.

MPV blood test results cannot confirm a diagnosis but are considered alongside other measures to help reach one.

This article discusses what to expect with an MPV blood test and how MPV levels are interpreted. It also covers conditions associated with high and low MPV results.

What Does an MPV Test Tell You?

The MPV blood test can reveal two important pieces of information:

• Platelet size: The size of your platelets indicates how old they are. The cells are bigger when they first come out of the bone marrow, where they are produced. Smaller platelets are usually older.
• How active these cells are: Platelets that are not functioning as they should interfere with hemostasis (stopping of blood flow) and thrombosis (clotting).
  

How to Prepare for an MPV Blood Test

Typically, you don't have to do anything to prepare for an MPV blood test.

An MPV blood test may be run on its own or as part of a complete blood count (CBC), which measures MPV and other components of your blood. If you are having other blood work done at the same time as your MPV test, your provider may want you to fast (avoid eating or drinking anything but water) for several hours beforehand.

They will let you know if this is necessary. If you're not sure, ask so you can avoid having to be re-tested.

What to Expect During an MPV Blood Test

All that's needed for an MPV test is a sample of your blood. A healthcare professional will use a small needle to draw blood from a vein in your arm into a test tube.

Once the blood is drawn, your provider will place a bandage on your arm. The whole thing usually takes less than five minutes. You may have slight pain or bruising at the spot where the needle was put in.

The blood is sent to a lab, where your platelets are closely examined under a microscope. Your healthcare provider will get a report with the results and communicate them to you.

Should I Worry About High MPV?

A high MPV (more than 12 femtoliters) is usually a sign that there are more young platelets circulating in your bloodstream.

One reason for this is blood loss due to trauma or a procedure, such as major surgery. In these instances, your body uses up platelets to repair the wound and stop the blood loss. In response, your bone marrow makes more megakaryocytes, cells that become young, large platelets, and your MPV rises.

But blood loss isn't the only possible cause for high MPV, which is why additional investigation is needed. In particular, MPV results are considered alongside platelet count.

A high MPV with the following platelet counts can suggest associated conditions:

• Low platelet count and high MPV occurs when platelets are destroyed, usually by antibodies, an infection, or toxins. For example, immune thrombocytopenic purpura (ITP) is a platelet deficiency caused by the destruction of platelets without a known cause.
• High platelet count and high MPV can occur when the bone marrow makes too many platelets, typically due to a genetic mutation or cancer.
• Normal platelet count and high MPV suggests conditions such as hyperthyroidism or chronic myelogenous leukemia (CML), a type of cancer.

Conditions that may be associated with an elevated MPV and variable platelet counts include:

• Bernard-Soulier disease (giant platelet syndrome)
• Bone marrow stimulating drugs, such as erythropoietin or thrombopoietin
• Diabetes mellitus
• Genetic abnormalities in platelets
• Heart disease or artificial heart valves
• Hyperthyroidism
• Non-alcoholic liver disease
• Pre-eclampsia (toxemia of pregnancy) and HELLP syndrome
• Respiratory diseases
• Sepsis

What Does It Mean When Your MPV Is Low?

Low MPV levels (less than 8 femtoliters) generally suggest that most of your platelets are older and that your bone marrow has slowed down production of these cells.

Here too, your total platelet count can help provide insight about the cause.

A low MPV with the following platelet counts can suggest related conditions:

• Low platelet count and low MPV points toward bone marrow disorders that slow down or decrease the production of platelets, such as aplastic anemia.
• High platelet count and low MPV often signifies an infection, inflammation, or cancer.
• Normal platelet count and low MPV is common with chronic kidney failure.

Conditions that may be associated with a low MPV and variable platelet counts include:

• Bone marrow failure
• Lupus
• Splenomegaly (enlargement of the spleen), which often causes platelets to be trapped in the spleen
• Medications that suppress platelet formation, such as chemotherapy
• Hypothyroidism
• Iron deficiency anemia
• HIV/AIDS

Other Factors That Can Affect MPV Test Results

It's possible for MPV results to be high or low due to factors unrelated to disease or a specific condition. Platelet volume (and count) can be affected by factors such as:

• People who live at low altitudes (below sea level) may have higher than average platelet counts. Those who live at high altitudes may have a high MPV, which may be a possible risk factor for heart disease.
• Smoking and high glucose levels (without a diagnosis of diabetes) have all been associated with a high MPV in men.
• Menstruation and oral contraceptives are associated with high MPV in women.
• Certain medications, such as statins, can lead to a low MPV.

Information about your health history, lifestyle, and environment should be carefully considered when a practitioner is interpreting MPV results. Be sure to share any such information with them so they can take it into account.

Summary

A mean platelet volume (MPV) test is done using a sample of blood. It shows how big your platelets are. If the cells are smaller than usual, you have a low MPV. If they are larger than usual, this is a high MPV.

Various health conditions and diseases can result in abnormal MPV levels. However, MPV results alone cannot diagnose a disease. To do this, you will need additional testing.