DIAGNOSIS OF PLEURAL EFFUSION IN ADULTS

Many diseases may cause pleural effusion, but congestive heart failure, pneumonia, tuberculosis and cancer are the most common. The study of the patient begins with a complete clinical history, and physical examination; then, the physician must analyze the pleural fluid, making a diagnostic thoracocentesis, to know if it is an exudate or trasudate based on Light's criteria. This discrimination is important because diagnostic and therapeutical alternatives depend on it. The biochemical characteristics of the fluid are important for the diagnosis, but other features are being studied. Adenosine deaminase, polymerase chain reaction and interferon gamma are important for tuberculosis pleural effusions diagnosis. ;Probrain natriuretic peptide is an useful marker for the diagnosis of pleural effusions from heart failure. TNF-alpha, IL-8 and myeloperoxidase are important new tests for the differentiation between infectious and non infectious pleural effusions. In this review, the so called abbreviated Light's criteria, and the value of protein concentration and lactate dehydrogenase concentration in pleural effusion are revisited. Other procedures that are mainly used in regular practice are percutaneous pleural biopsy and videothoracocospy. In spite of all the diagnosis methodology described above, in 5-10% of the cases the etiologic diagnosis of exudative pleural effusion cannot be reached.