Generality
MPV stands for Mean platelet volume - average platelet volume ; in practice, therefore, this parameter tells us how large our platelets are on average :
the higher the MPV, the greater the average platelet size.
What's this
Platelets (or thrombocytes) are small blood cells, disc-shaped and between 2 and 3 µm in diameter, produced by bone marrow. These elements are fundamental for hemostasis, as well as for blood coagulation. In the event that a blood vessel should be damaged, the platelets take care of adhering to the wall, aggregating and forming a cap that will temporarily limit the damage and stop the flow of blood to the outside.
Platelets survive in the bloodstream for about 8-10 days and the bone marrow must continuously produce new elements to replace those that are degraded, consumed and / or lost during bleeding.
The mean platelet volume (MPV) is a parameter that indicates the average size of these cells and is typically included in blood tests as part of the blood count .
Several factors can affect the normal dimensions of the plates:
- In the event that the bone marrow is subject to dysfunctions, the volume of platelets produced could be reduced;
- In the case in which the quantity of platelets synthesized is, however, insufficient, the bone marrow can try to make up for this deficiency by producing larger plates.
It is also necessary to take into account the fact that the newly produced platelets have a greater volume, while those that are now in circulation have tended to become smaller. In other words, young platelets are characterized by an increased average volume (> MPV) compared to older ones.
Why do you measure
The average volume (MPV) is a calculation performed by an automated instrument that reflects the size of the platelets present in the patient's blood . MPV is evaluated by the physician to obtain additional information about thrombocytes and / or to define the cause of a low or high count of these blood cells.
This parameter helps to diagnose and / or monitor diseases, such as haemostasis disorders, myeloproliferative syndromes and inflammatory diseases.
Associated examinations
The mean volume (MPV) must necessarily be evaluated together with the other platelet indices, such as the total number (PLT) and the blood platelet concentration (PCT).
The parameter can also be compared to one or more platelet function tests and / or other tests for the evaluation of coagulation, such as PT (Prothrombin time) and PTT (Partial Thromboplastin Time).
Normal values
There is no normal MPV for all, but normal MPV for a given number of platelets; in fact, the slower the platelet production rate is, the lower the MPV is.
In fact, the young platelet has a cell volume greater than an adult platelet, whereby in the presence of an increased synthesis there is a general increase in the average platelet volume (MPV).
Since the average platelet volume is higher when the body increases platelet synthesis, the MPV test can be used to obtain information on the production of platelets by the bone marrow.
A typical normal range for MPV is between 9.7 and 12.8 fL (femtoliters), which equals spheres of 2.65 - 2.9 µm in diameter.
MPV High - Causes
The possible causes of high MPV include:
- Platelet;
- Myeloproliferative syndromes;
- Idiopathic thrombocytopenic purpura;
- Heart attack;
- arterial;
- Mediterranean macrothrombocytosis;
- Removal of the spleen;
- Diabetes;
- Bernard-Soulier syndrome;
- Transient medullary hypoplasia;
- Preeclampsia;
- Inflammatory bowel disease.
Low MPV - Causes
Low MPV values are recorded in the event of:
- Wiscott Aldrich syndrome;
- Aplastic anemia;
- Bone marrow platelet depression (B12 and folate deficiency, chemotherapy, neoplastic infiltration, hypersplenism).
Consequences
Low MPV values predispose to bleeding.
Various studies, in fact, suggest that the larger platelets are functionally more active in the coagulation processes.
How to measure it
MPV is measured using an automated haemocytometric analysis tool. A sample of blood from a vein in the arm, usually in the morning and fasting, is then taken from the patient.
Furthermore, considering that the platelets may tend to clump together, distorting the "automatic" results, it may be necessary to analyze the sample under a microscope.
Preparation
To undergo blood sampling, it is necessary to abstain from food and drink for at least 8-10 hours.
Interpretation of Results
To identify any dysfunctions and pathologies, the value of the average platelet volume must necessarily be compared with the total platelet count. Typically, a lower production of thrombocytes is associated with low MPV, both in terms of frequency and quantity. On the contrary, instead, high values are associated with a frequent and quantitatively significant production of platelets.
An increase in the number of large platelets (high MPV) in a person with low platelet counts suggests that the bone marrow is producing thrombocytes and releases them into the circulation very quickly. By contrast, MPV may be low in people with low platelet counts following a bone marrow disorder.
Among the most important causes determining a low value of MPV are aplastic anemia, vitamin B12 and folic acid deficiencies, hypersplenism and Wiskott-Aldrich syndrome.
An increase in the average platelet volume may depend, instead, on phenomena of intravascular coagulation, diabetes and myeloproliferative disorders. Smoking and obesity can affect the outcome of the exam.
MPV and cardiovascular risk
- High values of MPV increase the risk of stroke and myocardial infarction, therefore they are associated with an increased cardiovascular and cerebrovascular mortality. The risk becomes concrete for MPV values higher than 12.0 fL. In fact, an excessive tendency to platelet aggregation increases the risk of thrombosis and embolism.
- MPV is higher in obese people and in those with other cardiovascular risk factors, such as diabetes or smoking.
- The essential fatty acids of the omega three series can help reduce MPV and the tendency to platelet aggregation in healthy subjects.
