Platelets or thrombocytes play a pivotal role in the coagulation process, and medical laboratory scientists are at the forefront of platelet testing. Although platelets are non-nucleated, they house a complex biochemical structure of granules, exterior proteins, and enzymes which promote and accentuate their activities. Platelets act in the initiation of the clotting process, where they adhere to damaged tissue and then form a platelet plug or aggregate. If this happens, then platelets signal the coagulation factors and a solid clot if formed is eventually dissolved. Adhesion and aggregations are vital to the subsequent formation of a viable clot and depend upon adequate number of platelets as well as the adequate physiologic functioning of platelets. Both are these are complicated and underappreciated processes. Bleeding may occur from inherited platelet abnormalities, quantitative abnormalities, or conditions which consume platelets. Presently, there are several drugs available which inhibit the aggregation process in individuals prone to stroke or heart attack. Plavix (clopidogrel) is a widely used drug which inhibits aggregation by preventing Adenosine diphosphate (ADP) from binding to platelets. Aspirin also inhibits the action of platelets.

Your challenge is to understand how to examine platelets on a peripheral smear, to produce a platelet estimate, to compare this estimate to the reference value, and to notice morphologic variations in platelets.