Exudative Pleural EffusionTransudative Pleural effusionExudative pleural effusion occurs when local factors that influence the formation and absorption of pleural fluid are altered.Transudative pleural effusion occurs when systemic factors that influence the formation and absorption of pleural fluid are altered.LIGHT's CRITERIATotal serum protein > 3 gm/dlPleural fluid protein/serum protein > 0.5Pleural fluid LDH/serum LDH > 0.6Pleural fluid LDH >2/3rd upper limit of serumTotal serum protein <3 gm/dlPleural fluid protein/serum protein < 0.5Pleural fluid LDH/serum LDH < 0.6Pleural fluid LDH <2/3rd upper limit of serumCausesNeoplasms - metastatic diseases, mesothelioma Infections - bacterial, viral, fungal, parasitic tuberculosis Pulmonary embolism Collagen vascular disorders - SLE, rheumatoid ahritis, Wegener's granulomatosis Gastrointestinal diseases UraemiaMeig's syndrome Chylothorax, hemothorax Ovarian hyperstimulation syndrome Drug-induced - bromocriptine, amiodarone, nitrofurantoin, dantrolene Congestive hea failureCirrhosisTrapped lung Nephrotic syndromeHypoalbuminemiaHepatic hydrothoraxPeritoneal dialysisConstrictive pericarditis SVC obstructionMyxedemaUrinothoraxRight-sided pleural effusionLeft sided pleural effusionCCF, CRF Liver cirrhosis with poal hypeensionAmoebic liver abscess Subphrenic abscessThoracic duct involvement below D5 level Pancreatitis Pericardial inflammation Oesophagal ruptureLeft-sided subdiaphragmatic abscessThoracic duct involvement above D5 levelBilateral pleural effusionPleural effusion in AIDSCCF Meig's syndrome Pulmonary infarction HypoalbuminemiaMalignancy Kaposi sarcoma Parapneumonic effusion Tuberculosis Cryptococcosis Lymphoma (Refer: Harrison's Principles of Internal Medicine, 18th edition, pg no: 2181)