The platelet distribution width of 9.9fl is normal, because the normal range of platelet distribution width in peripheral blood is 9-17fl in general. Of course, the standard value of platelet distribution width may vary somewhat in different hospitals, but, in general, platelet distribution width of 9.9fl is normal. The so-called platelet distribution width is an index reflecting the dispersion of platelet volume size in peripheral blood, which is an index reflecting the uniformity of platelet volume size in peripheral blood. If the platelet distribution width is increased, it means that the platelets in peripheral blood are disparate in size, which is common in clinical diseases including immune thrombocytopenia, some patients with acute granulocytic leukemia, etc. If the platelet distribution width is decreased, it is commonly seen in bone marrow hypoplasmosis disorders, commonly aplastic anemia.