Platelet disorders: an overview

Thrombocytes or platelets are anucleated cells derived from megakaryocytes by process of megakaryopoiesis, with maturation time of 4-5 days. They are small and discoid in shape with size ranging from 2 to 4 mu m. The platelet concentration in blood varies between 150 000 and 400 000 cells/mu l of blood. They are involved in both hemostasis and wound healing. Hence, any abnormalities in platelets can lead to various bleeding disorders. Platelet disorders include thrombocythemia and thrombocytosis, thrombocytopenia and platelet dysfunction. Thrombocythemia and thrombocytosis are associated with increased platelet count because of overproduction of platelets. Thrombocytopenia includes decreased platelet count because of failed platelet production, increased sequestration of platelets in spleen, dilution of platelets and combination of these mechanisms. Platelet dysfunction can be because of intrinsic platelet defect or an extrinsic factor that alters the normal platelet function and can be hereditary or acquired. The following review provides a comprehensive overview of the above platelet disorders.