Platelet distribution width, abbreviated PDW, is an indicator of platelet volume size dispersion and is expressed as the coefficient of variation of the measured individual platelet volume size. A high platelet distribution width indicates the presence of significant platelet size heterogeneity, and giant platelets can reach a diameter of 20-50 microns or more. Common disorders include acute granulocytic leukemia, megaloblastic anemia, chronic granulocytic leukemia, splenectomy, splenic embolism, giant platelet syndrome, and embolic disease. It is also seen in autoimmune disorders such as autoimmune thrombocytopenic purpura, systemic lupus erythematosus, etc.