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→Platelet Number
==Tests Evaluating Primary Haemostasis==
==Tests Evaluating Primary Haemostasis==
Primary haemostasis is dependent on the activity of platelets and, to a lesser extent, the blood vessels themselves. Platelets are the smallest solid formed component of blood, and are non-nucleated, flattened disc-shaped structures<sup>1</sup>. Their activity leads to vascoconstriction and the formation of platelet plugs to occlude vessel defects. Platelets develop in the bone marrow, and have a life span of around 7.5 days. Around two thirds of platelets are found in the circulation at any one time, with the remainder residing in the spleen<sup>1</sup>.
===Platelet Number===
===Platelet Number===
The platelet count is of value when assessing bleeding disorders that occur with thrombocytopenai, uremia, liver disease or malignancies and for monitoring the course of disease associated with bone marrow failure. This test is indicated when the estimated platelet count on a blood smear appears abnormal. It is also part of a coagulation profile or work up. the mean platelet volume (MPV) is somtimes used in conjunction with a platelet count. The MPV indicates the uniformitiy of the size of the platelte population and is used for the differential diagnosis of throbocytopenia.
The platelet count is of value when assessing bleeding disorders that occur with thrombocytopenai, uremia, liver disease or malignancies and for monitoring the course of disease associated with bone marrow failure. This test is indicated when the estimated platelet count on a blood smear appears abnormal. It is also part of a coagulation profile or work up. the mean platelet volume (MPV) is somtimes used in conjunction with a platelet count. The MPV indicates the uniformitiy of the size of the platelte population and is used for the differential diagnosis of throbocytopenia.