Mean platelet volume reflects the average size of platelets, an important component of the blood. Platelets have an important role in blood clotting, particularly following injury. A mean platelet volume can give a good indication of how well the platelets are functioning. Depending on some factors like where you live, a normal platelet count may be high or low.
A mean platelet volume blood test is usually used as part of a full blood count alongside other red cell indices such as mean cell haemoglobin concentration, mean cell haemoglobin and mean corpuscular volume. A full blood count tells us about the different cells in the blood and the numbers of them available. Abnormalities may indicate the presence of illness or disease.
Blood contains three main components, red blood cells, white blood cells and platelets. Platelets are also called thrombocytes and their main function is to react to bleeding in the body by sticking together to initiate a blood clot and ultimately, stop the bleeding. They have no nucleus so are called anucleate cells. Platelets travel in the blood searching for any problems in structural integrity. So, if there is a wound, the platelets will work together to naturally stem the bleeding and clot the blood, preventing blood loss.
Upon the discovery of injury to a blood vessel, platelets interact with the subendothelial matrix. Usually blood vessels are lined with special cells called endothelial cells. However, when a blood vessel is injured the endothelial cells are lost and the subendothelial matrix is exposed. The matrix sends out strong signals which stimulate platelets to become activated and adhere to each other. The ability of the body to naturally stop the flow of blood is called haemostasis, abnormalities, however, can cause haemorrhage or blood clots to occur.
Inactivated platelets are circular in shape, however, when they become activated, platelets change to a spiky structure. The change in shape makes it easier for the platelets to stick to both the damaged vessel and to each other to plug the hole. A protein in the blood, fibrin, interacts with the platelets to help seal the wound by forming a net, trapping more activated platelets and red blood cells to seal the wound.
Because of their clotting properties, platelets have been shown to produce clots in diseased blood vessels called thrombosis. Usually, young platelets are larger in size compared to older ones which means the higher the platelet volume, the larger and younger the platelets in circulation are. Platelet volumes have been associated with conditions, including coronary artery disease, stroke, high blood pressure and diabetes.
Some research has shown a link between vitamin D deficiency and an increase in MPV. Although the vitamin has many important roles in the human body, it also reduces the expression of adhesion molecules which prevents platelet activation. Vitamin D also interferes with the anticoagulant balance in the blood, resulting in an increased MPV.
A high MPV is associated with a greater risk of thrombosis, the formation of a blood clot inside a blood vessel. Inflammatory diseases such as rheumatoid arthritis are linked with low MPV levels.
A low MPV level can be an indicator of many different conditions, including:
A high MPV level can signify:
Thrombocytopenia is caused by mild to severe bleeding which is responsible for the main symptoms of the condition. Mild thrombocytopenia usually doesn’t have any signs or symptoms and may be diagnosed through a routine blood test. However, it may cause purple, brown and red bruises called purpura or small red or purple dots on your skin, known as petechiae.
If you have an increased MPV caused by vitamin D deficiency, you may experience the following symptoms:
A high MPV could be a sign of vitamin D deficiency. Most of our intake of vitamin D comes from our exposure to the sun. Therefore, it is important, if you can, to spend some time outdoors, particularly in the summer months. However, over half of the adult population in the UK has insufficient vitamin D levels and approximately 16% have severe deficiency during the winter months. Due to the location of the UK, most of its population is at risk of vitamin D deficiency, but this is preventable through supplementation. Public Health England recommends all adults and children over the age of one should consider taking a daily vitamin D supplement. Whether it is solely a vitamin D supplement or a multivitamin which contains it, the supplement should contain at least 10mcg of vitamin D.
There is some evidence to suggest that MPV could be a predictor of endurance performance. Physical activity prevents cardiovascular morbidity and mortality, but it does lead to a temporary activation of the thrombotic system. In healthy individuals, fibrin activity is increased, but in individuals who have heart disease, their fibrin activity is compromised. Therefore, it is essential to seek medical advice before attempting strenuous physical activity.
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