In dengue fever, thrombocytopenia is ascribed to destruction of platelets by antiplatelet antibodies, disseminated intravascular coagulation, marrow suppression and peripheral sequestration of platelets. Platelet counts vary considerably during the course of illness, and patients may require platelet transfusion when the counts are <10000/mm3 [1]. Platelet count is expected to rise in the late critical or the recovery phase of the infection. Immature platelet fraction (IPFL, the percentage of immature platelets) can be used to fairly predict the rise or fall of platelet count during the course of dengue fever [2]. IPF defines the immature and larger platelets that have been recently released from the marrow, and have much larger RNA content than the mature platelets. A high IPF is usually found in either consumptive or recovering thrombocytopenic disorders, while a low IPF is characteristic of bone marrow　suppression [2]. IPF is identified by simple flow cytometry technique and the use of a nucleic acid specific dye (e.g., oxazine dye 0.0003%) in the optical platelet channel which is available in most hematology laboratories. The test is simple, inexpensive and reproducible [3]. An IPF reference range in healthy neonates is 4.1±1.8, and in children is 2.7±1.3 [4]. IPF has been shown to have a strong correlation with the recovery of platelet counts in patients with dengue fever [5]. Patients with no warning signs or symptoms but with NS1 positive and borderline platelet count keep the treating pediatrician under dilemma – whether to admit the patient or to observe. Performing IPF in dengue patients may help in decision for admitting or monitoring during recovery in dengue fever.

5. Dadu T, Sehgal K, Joshi M, Khodaiji S. Evaluation of the immature platelet fraction as an indicator of platelet recovery in dengue patients. Int J Lab Hematol. 2014;36:499-504.