Laboratory finding

00000000 Thrombocytopenia and haemoconcentration are constant findings in DHF. A drop in the platelet count to below 100 000 per mm3 is usually found between the third and eighth day of illness, often before or simultaneous with changes tn the haematocrit. A rise in the haematocrit level, indicating plasma leakage, is always present, even in non-shock cases, but is more pronounced in shock cases. Haemoconcentration with an increases in the haematocrit of 20% or more is considered to be definitive evidence of increased vascular permeability and plasma leakahe. It should be noted that the haematocrit level may be affected either by early volume replacement or by bleeding. The time-course relationship between a drop in the platelet count and a rapid rise in the haematocrit appears to be unique for DHF; both changes occur before defervescence and before the onset of shock.

00000000 In DHF, the white-blood-cell count may be variable at the onset of illness, ranging from leukopenia to mild leukocytosis, but a drop in the total white-blood-cell count due to a reduction in the number of neutrophils is virtually always observed near the end of the febrile phase of illness. Relative lymphocytosis, with the presence of atypical lymphocytes, is a common finding before defervescence or shock. A transient mild abluminuria is sometimes observed, and occuly blood is often found in the stool. In most cases, assays of coagulation or fibrinolytic factors show a reduction in fibrinogen, prothrombin, factor VIII. Factor XII, and antithrombin III. A reduction in a-antiplasmin (a-plasmin ingibitor) has been noted in some cases. In severe cases with marked liver dysfunction, reductions are observed in the levels of the prothrombin factors that are vitamin-K dependent, such as factors V, VII, IX and X. Partial thromboplastin time and prothrombin time are prolonged in about one-half and one-third of DHF patients, respectively. Thrombin time is prolonged in severe cases. Platelet function has also been found to be impaired. Serum complement levels, particularly that of C3, are reduced.

00000000 The other common findings are hypoproteinaemia (due to a loss of albumin), hyponatraemia, and elevated levels of serum aspartate aminotransferase. Metabloic acidosis may frequently be found in prolonged shock. Blood urea witrogen is elevated at the terminal stage of shock.

00000000 X-ray examination of the chest reveals pleural effusion, mostly on the right side, as a constant finding, and the extent of pleural effusion is correlated with the severity of disease. In shock, bilateral pleural effusion is a common finding.