Thrombocytopenia in patients with dengue virus infection in the Brazilian Amazon.

Thrombocytopenia may be occasionally observed in dengue fever (DF) but is a constant feature and one of the diagnostic criteria of dengue hemorrhagic fever (DHF). Its clinical presentation and relevance is still poorly described in the literature. Patients with fever and bleeding were referred to a tertiary care center in Manaus, in the Western Brazilian Amazon during the outbreak of dengue in 2001. They were hospitalized for clinical observation and supportive care. Platelet counts were performed on admission and throughout the hospitalization. Only patients with a serological confirmation or viral isolation of the dengue virus were included. One hundred and seventy eight patients were enrolled in the study (118 with DF and 60 with DHF). There was no association between the presence of active bleeding and the degree of thrombocytopenia on admission (P = 0.302). A positive tourniquet test, hematemesis and ecchymoses were more frequent in DHF patients (P < 0.05). Patients with DHF had lower platelet counts than patients with DF (P < 0.001). There was a positive correlation between platelet counts and plasma albumin levels (r = 0.217; P = 0.016) and a negative correlation with ALT values (r = -0.3; P = 0.001). Clinical manifestations of thrombocytopenia are not related only to the number of peripheral platelets in dengue infection, but its recovery is associated with clinical improvement. The level of platelets correlates with the vascular leakage of proteins and liver damage.