Thanks to recent changes in how our medical information is handled these days, there’s a chance you’ll see your bloodwork results before your doctor visit…and if a parameter is a bit out of range, it might set your mind racing. One such parameter is the mean platelet volume (MPV).
Bottom Line Personal asked hematologist Robert Negrin, MD, professor of medicine at Stanford University, to help us understand what MPV measures…why it sometimes matters…and why it’s important not to get hung up on it when it is high or low.
Platelet size
Despite containing the term “volume,” MPV in fact measures the average size of the platelets circulating in your blood. Platelets are a type of blood cell that helps us form blood clots. When we have a cut or other injury, platelets help initiate the blood-clotting and healing process.
Platelets are formed inside the bone marrow, in larger cells called megakaryocytes, which are bags of platelets. When things are functioning normally, appropriately sized fragments break off from the megakaryocytes in the form of platelets and are released from the bone marrow into the blood. These fragments naturally vary in size. The MPV test determines the average size of the platelets in a collected sample.
What is normal, high and low MPV?
Platelets usually fall between 7.5 femtoliters (fL) and 11.5 fL in size—a femtoliter is a unit of measure equal to one quadrillionth of a liter. An average platelet size below 7.5 fL is typically flagged as low…and one greater than 11.5 fL is considered high.
What diseases are linked to MPV?
Although an abnormal MPV result could be one factor in a disease or illness, MPV on its own is not diagnostic. A doctor cannot look at a high or low MPV result and conclude that you probably have X or Y disease. High MPV is more likely to indicate illness or disease than a low MPV.
High MPV may be one indicator of a myeloproliferative disorder, in which the megakaryocytes overproduce platelets. High MPV also might be related to a certain type of leukemia. And of course, having too many—and too large—platelets circulating creates the risk that a blood clot could form and cause a stroke or heart attack.
Low MPV, in combination with other indicators, could be linked to bone marrow suppression, a nutritional deficiency or reduced platelet production.
What do I do if my MPV is high or low?
If you get your lab results and see that your MPV is high or low but nothing else seems out of the ordinary, don’t start worrying about diseases. Simply ask your doctor about it. The diseases associated with abnormal MPV readings are almost always accompanied by other abnormalities in your bloodwork, symptoms and/or a medical history.
MPV is just one of many measurements on a standard blood test called a complete blood count (CBC). Others include total white blood cell count, hematocrit, amount of hemoglobin, mean corpuscular volume (MCV)—the average size of red blood cells—and total platelet count (how many platelets you have circulating). Technicians also perform a “blood smear” on the sample to examine the shapes of the blood cells, including platelets, and note any abnormalities. These parameters must be looked at holistically and not viewed individually out of context.
If you’re healthy and the other components of the blood test show nothing else out of the ordinary, your doctor is unlikely to be concerned if you have a slightly high or low MPV result. You typically would need some combination of abnormalities to prompt further investigation, such as a high MPV along with “abnormal platelet morphology” (weird platelet shape) or abnormalities in other blood cells.
A seemingly abnormal MPV reading also may be caused by the way in which the sample collection or analysis was performed, which sometimes causes the platelets to clump together and look bigger than they are. When retested, the reading could be normal.
