Understanding the Mean Platelet Volume (MPV) Test

The mean platelet volume (MPV) blood test measures the average size of platelets, the cells responsible for forming blood clots to slow blood loss, prevent infection, and promote healing. MPV results outside of the normal range—8.9 to 11.8 fL (femtoliters)—can indicate an underlying health condition.

Usually, newer platelets are larger in size than older platelets.

As such, a high mean platelet volume indicates an abundance of new blood platelets. This could be due to recovery from a recent blood loss (such as a trauma or major surgery). A high MPV can also signify heart disease, diabetes, hyperthyroidism, liver disease, or another health condition. 

A low mean platelet volume means the platelets are older on average, which could indicate bone marrow failure. Other causes for low MPV include hypothyroidism, lupus, an enlarged spleen, or iron deficiency anemia. 

Why Is an MPV Blood Test Performed?

This measurement is taken as a part of a standard complete blood count (CBC), a blood test used in routine health screening and for monitoring many health conditions. The CBC measures your total platelet count as well as your platelet indices, including MPV and platelet distribution width (PDW). PDW reflects the variation in the width of your platelets.

These indices are details about your platelets that provide a fuller description of what your actual platelets look like. In fact, even if you have a normal platelet count, abnormal indices may alert your healthcare provider to a problem.

Your healthcare provider may order this test as part of a routine exam or if you have symptoms that signal a bleeding disorder. These symptoms include:

• Bleeding that takes a long time to stop
• Bleeding from places like the nose or gums
• Blood in urine or stool
• Small red or purplish spots on the skin
• Easy bruising
• Heavy menstrual periods
• Feeling weak or faint
• Burning in the hands or feet

To obtain an MPV value, your blood is drawn into a purple top tube that contains an anticoagulant. This prevents the blood from clotting and giving an abnormal result for both the platelet count and MPV.

A normal MPV is between 8.9 and 11.8 fL. However, labs vary as to their specific reference (normal) ranges, so check your CBC report for the range for your results.

The MPV test alone cannot confirm a diagnosis. However, your healthcare provider will use it along with other tests and health information to interpret the results.

Why Mean Platelet Volume May Be High

A high MPV is usually a sign that there are more young platelets circulating in your bloodstream.

Platelets are made in the bone marrow by large cells called megakaryocytes. The platelets, which are released into the bloodstream from the bone marrow, are actually pieces of the megakaryocytes.

After blood loss due to trauma or a procedure such as major surgery, your body uses up platelets to repair the wound and stop the blood loss. In response, your bone marrow makes more megakaryocytes, which become young, large platelets, and your MPV rises.

You may have a high MPV with a low, normal, or high platelet count, and looking at these results together helps provide a diagnosis.

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

• Low platelet count along with 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 along with high MPV can occur when the bone marrow makes too many platelets, typically due to a genetic mutation or cancer.
• Normal platelet count along with high MPV suggests conditions such as hyperthyroidism or chronic myelogenous leukemia (CML), a type of cancer.

High MPV Test Results With Variable Platelet Counts

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

Why Mean Platelet Volume May Be Low

A low MPV generally suggests that most of your platelets are older and that your bone marrow has slowed down production of platelets. 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 along with low MPV points toward bone marrow disorders that slow down or decrease the production of platelets, such as aplastic anemia.
• High platelet count along with low MPV often signifies an infection, inflammation, or cancer.
• Normal platelet count along with low MPV is common with chronic kidney failure.

Low MPV Levels With Variable Platelet Counts

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

Factors Affecting MPV Test Results

It's possible for MPV results to be artificially high or low due to factors that are not related to disease or a specific condition. Platelet count and volume can be affected by factors such as altitude, medications, and health risk factors:

• 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, high blood pressure, 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.
• Strenuous exercise has also been associated with an increase in platelet count if it is severe enough to cause tissue damage.

It's important to keep these factors in mind, knowing that your platelet count and MPV may undergo some variation. That said, information about a person's health history, lifestyle, and environment should be carefully considered when interpreting these test results.

Further Testing

While MPV is a helpful test, it is not diagnostic. And some conditions, such as cancer, can be associated with a low or a high MPV. Your MPV results are considered along with your other symptoms. For example, you may need a thyroid test if you have symptoms of hyperthyroidism or hypothyroidism.

Similarly, if you have unexplained weight loss or bruising with an elevated or low MPV, you may need further testing with a bone marrow biopsy, which can identify certain types of cancer and may determine whether your bone marrow is not functioning as it should.

A Word From Verywell

Some studies suggest that MPV may be associated with predicting conditions such as heart attacks and strokes. Similarly, there may be an association between MPV and some nutritional deficiencies such as vitamin D and vitamin B12.

Overall, while it is certainly a helpful value to consider, MPV should be evaluated along with your overall health status and your other lab results.