Platelets are essential components of the blood that play a vital role in hemostasis and wound healing. In this article, we will explore the characteristics and functions of platelets, as well as their normal and abnormal values. We will also discuss the MPV blood test and its significance.
What are Platelets and How are They Formed?
Platelets are small, anucleate fragments that develop from the cytoplasm of megakaryocytes. They have a characteristic discoid shape and are involved in primary and secondary hemostasis. The production of platelets is regulated by a glycoprotein called thrombopoietin, which is synthesized in the liver and kidneys.
What is the Life Span of Platelets and How are They Measured?
Once they enter circulation, platelets have a life span of 7 to 10 days. The platelet count is used to evaluate the integrity of the hematopoietic and hemostatic systems. A normal platelet count ranges from 150,000 to 400,000/cmm, and it can be measured manually under a microscope or by an automated hematology cell analyzer. Specimen requirements for platelet count measurement are whole blood with EDTA.
What Causes Abnormal Platelet Counts?
Thrombocytopaenia, a decrease in the number of platelets in peripheral blood below normal levels (<150,000/cmm), can result from various mechanisms. These include increased peripheral destruction of platelets, decreased production of platelets in the bone marrow, dilutional thrombocytopaenia, or sequestration in an enlarged spleen. Platelet counts between 150,000 and 50,000/cmm are generally not associated with clinically significant bleeding, while counts between 50,000 and 20,000/cmm can cause bleeding with trauma or surgery, or mild spontaneous bleeding. A platelet count below 20,000/cmm is associated with a high risk of spontaneous, severe hemorrhage. On the other hand, thrombocytosis, a platelet count greater than 400,000/cmm, can occur due to reactive or primary causes.
What is MPV and How is it Tested?
The Mean Platelet Volume (MPV) is a measure of the average size of platelets. A small MPV (<7 fl) indicates small platelets, a normal MPV (7-11 fl) indicates normal platelets, and a large MPV (>11 fl) indicates large platelets. MPV is increased when thrombocytopaenia is due to peripheral platelet destruction, as platelet production is stimulated with the release of large platelets in circulation. MPV is also increased in myeloproliferative disorders. The MPV blood test is a useful tool to differentiate the cause of thrombocytopaenia.
In summary, platelets play a critical role in hemostasis and wound healing. Platelet count and MPV are essential parameters used to evaluate the hematopoietic and hemostatic systems. Abnormalities in these parameters can indicate various underlying pathological conditions. Therefore, timely and accurate measurement of platelet count and MPV can aid in the diagnosis and management of platelet disorders.