Large platelets are generally defined as platelets with a diameter of more than 10 μm. The ratio of large platelets is generally 8%-16% of all platelets in the peripheral blood. An increase in the ratio of large platelets is common in cases of increased platelet destruction in peripheral blood with good bone marrow compensation, such as patients with immune thrombocytopenic purpura, and in leukemia patients with bone marrow suppression after chemotherapy, and if the bone marrow suppression is lifted, an increase in the ratio of large platelets will occur. Decreased platelet ratios are common in cases of poor bone marrow hematopoiesis, such as patients with aplastic anemia, while patients with malignancies such as leukemia or multiple myeloma, who develop myelosuppression after chemotherapy, will also experience a decrease in platelet ratios. Therefore, the ratio of large platelets can reflect whether the bone marrow hematopoietic function is vigorous or reduced.