PLATELET DISORDERS

Platelets are non-nucleated blood cells produced in bone marrow as well as other tissues by fragmentation of megakaryocytes, under control of Thrombopoietin hormone.

Normal platelet count varies between 1,50,000 and 4,50,000 cells/mm³. These cells have in vivo life span of 7-10 days, but in vitro half-life in only 6-8 hours.

Purpura is a clinical abnormality of platelet-or vascular-phase of hemostasis. Platelet defects may be quantitative (thrombocytopenic purpura) or qualitative (non-thrombocytopenic purpura) (Table 19.21).

19.11.1