Platelet distribution width, abbreviated as PDW, is a measure of the dispersion of platelet volume size, which is expressed as the coefficient of variation of the volume size of the individual platelets measured.Decreased PDW indicates high platelet homogeneity, which is common in normal people and is a sign of normal bone marrow hematopoietic function.Increased PDW indicates a disparity in platelet size, which is commonly seen in acute myelogenous leukemia, immune thrombocytopenic purpura, megakaryocytic anemia, chronic granulocytic leukemia, splenectomy, giant platelet syndrome, thrombotic diseases, and so on. anemia, chronic granulocytic leukemia, splenectomy, giant platelet syndrome, thrombophilia, and so on. It is also seen in leukemia patients after chemotherapy, after the release of myelosuppression, due to the large size of the newborn platelets, there will also be a high PDW.