[Pleural effusion--which diagnosis is significant?].

Although many different diseases may cause a pleural effusion the most common causes are congestive heart failure, pneumonie, and cancer. The first step in the diagnosis of pleural effusion is the distinction between exudates and transudates. Because of their high sensitivity Light's criteria, which differentiate transudative effusions from exudative effusions by measuring the levels of total protein and lactate dehydrogenase in the pleural fluid and serum, have become the standard method for making this distinction. Aim of this article was to mention the various parameters and their usefulness in closer characterication of pleural effusion.