see: [Dunn pleural effusion](x-devonthink-item://4EE25610-B4F8-4A46-B202-C7A4EEE8581F) # Causes of pleural effusions - **transudates** - [[Congestive Heart Failure|CHF]] - cirrhosis - nephrotic syndrome - hypoalbuminemia - myxoedema - peritoneal dialysis - [[glomerulonephritis]] - SVC obstruction - [[Pulmonary Embolism|PE]] - **Exudative** - *malignancy* - lung cancer, mesothelioma, pulm or pleural mets, lymphoma - *infections* - bacterial pneumonia - bronchiectasis - lung abscess / empyema - [[Tuberculosis]] - viral illness - connective tissue disease - rheumatoid arthritis - SLE - abdo/GI disorders - [[pancreatitis]] - esophageal rupture - abdo surger - misc - pulm infarction - uraemia - drug rxn - postpartum - chylothorax # evaluate pleural fluid normal: - protein < 2% - WCC <1000 mm3 - glucose ∝ plasma - LDH < 50% plasma ## Light's criteria Not to be confused with ([[Spontaneous Bacterial Peritonitis#ascites tap]]) for differentiating transudates from exudates (criteria means it is *exudate* 1. pleural fluid protein/serum protein > 0.5 2. pleural LDH : serum LDH > 0.6 3. pleural LDH >2/3 upper limit of normal serum LDH level > **mnemonic** (thanks Matt!) for *exudate* > POS and LOG > Protein ratio - P >0.5 > LDH ratio - >0.6 ## evaluate exudative effusions - lymphocytes reflect longstanding effusion - lymphocytes >50% suggest malignancy (eg lymphoma) or TB