MPV blood test: what high or low MPV means

What MPV measures

Platelets are small cell fragments made in the bone marrow. When you bleed, they clump together to help form a clot. A CBC counts them (the platelet count) and measures their average size (MPV).

Newer platelets tend to be larger. So MPV gives a rough sense of how actively your marrow is making platelets, and it is most useful when your platelet count is low or high. A normal adult platelet count is about 150,000 to 400,000 per microliter.

What a high MPV can mean

Larger platelets can mean the marrow is releasing many new ones, often because older platelets are being used up or destroyed faster. Conditions linked with a high MPV include:

• Immune thrombocytopenia (ITP), where the immune system destroys platelets and the marrow makes larger new ones to keep up.
• Cardiovascular disease and diabetes. Studies link a higher MPV with heart and blood vessel disease.
• An overactive thyroid.
• Low vitamin B12, folate or vitamin D.
• Inflammatory conditions such as Crohn's disease, and preeclampsia in pregnancy.
• Bone marrow conditions (myeloproliferative disorders) and some cancers.
• Inherited large-platelet conditions, which are rare.

What a low MPV can mean

Smaller platelets can mean the marrow is making fewer new ones. Conditions linked with a low MPV include:

• Medications that slow the marrow, such as some chemotherapy drugs.
• Aplastic anemia and other conditions where the marrow makes too few cells.
• Lupus.
• Some causes of a high platelet count (thrombocytosis).
• Rare inherited conditions such as Wiskott-Aldrich syndrome.

Everyday factors can shift MPV too: altitude, pregnancy, your period, regular hard exercise, physical or emotional stress, and medications such as birth control pills.

What to do with an abnormal result

1. Look at your platelet count first. A high or low MPV with a normal platelet count and normal other results is usually something to recheck, not chase.
2. If the platelet count is also abnormal, ask your clinician what the pair suggests and whether a blood smear or repeat CBC makes sense.
3. Mention anything that could have shifted it, like recent hard exercise, a new medication, pregnancy or a recent illness.
4. Compare results from the same lab. Labs measure MPV with different machines and set different ranges, so a result from one lab may not match another.

See a clinician promptly if an abnormal MPV or platelet count comes with easy or unexplained bruising, tiny red or purple spots on the skin, frequent nosebleeds or bleeding gums, blood in your urine or stool, or a swollen, painful leg or sudden shortness of breath.