Mean Platelet Volume (MPV) is a measure of the volume of a large number of platelets determined by an automated analyzer. Mean Platelet Volume is to platelets as Mean Corpuscular Volume (MCV) is to the Red Blood Cells. Like both Red Blood Cell Count and Mean Corpuscular Volume, both of Platelet Count and Mean Platelet Volume are a part of the Complete Blood Count test and they are both ordered routinely to with the Complete and Differential Blood Count. Mean Platelet Volume test is helpful in the evaluation of platelet disorders, especially Thrombocytopenia (Low Platelet Cout).
Mean Platelet Volume varies with total platelet production. In cases of thrombocytopenia despite a normal reactive bone marrow (e.g., hypersplenism), the normal bone marrow releases immature platelets in an attempt to maintain a normal platelet count. These immature platelets are larger, and the MPV is increased. When bone marrow production of platelets is inadequate, the platelets that are released are small. This will be reflected as a low MPV; this makes the MPV very useful in the differential diagnosis of thrombocytopenic disorders.
Causes of High Mean Platelet Volume
- Some diseases are associated with Thrombocytopenia and a normally reactive bone marrow which will produce a great number of immature platelets in an attempt to maintain a normal platelet count. These immature platelets are large and increase the MPV. Diseases associated with Thrombocytopenia and lead to High MPV include Valvular Heart Disease, Massive Hemorrhage, and Immune Thrombocytopenia. Examples of Immune Thrombocytopenia include Idiopathic Thrombocytopenia, Neonatal Thrombocytopenia, Posttransfusion Thrombocytopenia, and Drug induced Thrombocytopenia.
- Vitamin B12 or folate deficiency: Megaloblastic changes affect the megakaryocyte just as the erythroid line is affected. The platelets that are produced are larger and may even be nucleated. The MPV is increased.
- Myelogenous leukemia: Large, abnormal platelets are formed by neoplastic megakaryocytes if they are involved in the leukemic process. The MPV will increase.
Causes of Low Mean Platelet Volume
- Wiskott-Aldrich Syndrome: This syndrome is characterized by eczema, immune deficiency, thrombocytopenia, and small platelets.
- When bone marrow production of platelets is inadequate, the platelets that are released are small. MPV will be reduced. This is usually caused by Aplastic Anemia and Chemotherapy-induced Myelosuppression.