Introduction: Dengue is a major public health problem in tropical countries like India. The role of novel platelet indices is not well established for routine clinical use in dengue infection. Our study was undertaken to compare the platelet indices PLT count, MPV, PDW and PCT in serologically positive Dengue cases with that of control group and to assess the differences in platelet indices, if any between serologically antigen and antibody positive Dengue cases. Methods: Serologically NS1 antigen, IgM, IgG antibody positive 521 dengue cases detected by rapid ICT card test and 158 serologically dengue negative controls with normal platelet counts were studied. The PLT count, MPV, PCT and PDW in both case and control groups were measured by Beckman LH780 hematology analyzer and compared by statistical analysis. Results: PLT count and PCT were significantly lower (P< 0.005), MPV and PDW were significantly higher (P<0.005, 0.384 respectively) in dengue cases when compared to controls. Low PLT count, high MPV and low PCT were significantly associated with NS1 antigen, IgM, IgG antibody positivity. PLT count <150x109 /L was sensitive, MPV >8.5FL and PCT <0.14% were specific for dengue infection. PDW was not an accurate marker.Conclusion: Low PLT count, high MPV and low PCT were significantly associated with NS1 antigen, IgM and IgG antibody positivity. Platelet count <150x109 /L showed sensitivity, MPV > 8.5FL and PCT <0.14% showed specificity for dengue infection.

Keywords : Dengue; Mean Platelet Volume; Platelet Count; Plateletcrit; Platelet Distribution Width.