RESUMO
The authors relate the data on the importance of a biochemical analysis of the pleural fluid for the differential diagnosis of pleurisy and identification of the early signs of pleural fluid suppuration. For the purposes of the differential diagnosis between transudates and exudates measurements are made of the protein content and LDH activity in the pleural fluid. The exudate protein/serum protein and exudate LDH/serum LDH ratios are computed in necessary cases. The high prothrombin index (over 100%) and the level of lysozyme (over 25 (micrograms/ml) in the pleural fluid provide evidence in favour of the tuberculous etiology of pleurisy. The low level of glucose (under 2 mmol/l), high activity of LDH (over 6.2 mmol/l) and the negative ethanol test may point to the initial signs of exudate suppuration.
