Platelets, also known as thrombocytes, are cells that form a major proportion of both human and animal blood. Microscopically, they look like little thorned or spiky ovals, and they can only be viewed microscopically, as the average size is about four hundred thousandths of an inch (1 to 3.5 um). Platelets are actually fragments of the cells in bone marrow, called megakaryocytes. The normal value ranges from 150,000-350,000/cumm of blood..
Platelets help in coagulation. Once a blood vessel is injured, platelet activation is stimulated. The platelets attach to the injured blood vessel wall by binding to the collagen. This is termed platelet adhesion. Once more and more platelet come together to the site ,it is termed platelet aggregation. Together with other clotting factors found in the blood, the thrombocytes help produce a solid clot that prevents further bleeding.
A patient with platelet disorder manifest with petechiae (pinpoint lesions on the skin), and mucous membrane bleeding like epistaxis (nose bleeding).Once this are seen especially if there is a family history, the patient must be seen by a hematologist
References:
http://www.wisegreek.com/ visited November 13, 2010
Laboratory Diagnosis 20th Edition by John Bernard Henry
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