Currently, there are many laboratory methods to help diagnose pleural effusion accurately and easily, even in the case of small pleural effusion, malignant pleural effusion. To diagnose pleural effusion, it is necessary to rely on clinical and subclinical symptoms.

Pleural effusion is not a disease but a syndrome caused by many different diseases. To diagnose pleural effusion as well as the cause of this condition, pleural effusion tests need to be done.