Large platelets are platelets with a diameter of more than 10 μm and a volume of more than 11 fl. Generally, large platelets account for 8%-16% of all platelets in peripheral blood, and a decrease in the proportion of large platelets below 8% and an increase in the proportion of platelets above 16%. A decrease in the proportion of large platelets is common in bone marrow hematopoietic diseases, most commonly in aplastic anemia and leukemia patients after chemotherapy, when the bone marrow becomes myelosuppressed. An elevated percentage of large platelets is common when there is excessive destruction of platelets in the peripheral blood, but the bone marrow is compensating vigorously, and the most common diseases are immune thrombocytopenia and purpura. In addition, some acute myeloid leukemias, also present with a high ratio of large platelets.