High Fluorescence Lymphocyte Count and Immature Platelet Fraction; “Can these Two Parameters Reliably Distinguish between Dengue and ITP?”

Abstract: Objective: Thrombocytopenia is a frequent finding in Dengue fever. Immune Thrombocytopenia (ITP) is a diagnosis of exclusion and is not associated with febrile illness. Ignoring fever, low platelet count and clinical signs may be similar in both conditions. Peripheral film finding in Dengue fever shows many reactive lymphocytes. Enumeration of these reactive lymphocytes as high fluorescence lymphocyte count (HFLC) and computing immature fraction of platelets (IPF) may be useful in differentiating these two disorders as soon as the blood sample is analyzed on XN-1000 hematology analyzer. Materials and Methods: A cross-sectional study was conducted at National Institute of Blood Disease and Bone Marrow transplantation from January to July 2019 during (Dengue season); blood samples from emergency room were analyzed on XN-1000 hematology analyzer for complete blood count and IPF. Samples with thrombocytopenia were checked for IPF count and HFLC from the extended research parameter data of the analyzer. Patients presenting with fever, had Dengue NS-1 tested. Detailed history & examination was recorded from the patients. Results: Out of the 124 patients, 62 (50%) patients of Dengue and ITP respectively. Male to female ratio was 2:1. Mean age in Dengue was 25.52±10.46 years while 34.44 + 20.82 years in ITP group. Mean platelet count was significantly higher in dengue than ITP patients (120.59 ± 80.28 x109/L versus 41.84 ±38.62 x109/L) (p<0.001). HFLC was 11.71± 7.17% in Dengue fever while 0.198±0.25% in ITP patients whereas IPF in ITP group was 21.91 ± 16.09% while 8.79± 4.39%in Dengue patients were found to be significant i.e. (p<0.001). Conclusion: Excluding fever, thrombocytopenia, presence of increased number of HFLC and low or normal IPF can reliably a predictor of a diagnosis in Dengue season. Keywords: High fluorescence lymphocyte counts, Immature platelet functions, Dengue, Immune thrombocytopenia, Resource constraint Laboratories, Research parameters.