Increased hydrostatic pressure within pleural capillaries (such as congestive heart failure), increased pleural permeability (such as pleural inflammation, tumors), decreased colloid osmotic pressure within pleural capillaries (such as hypoproteinemia, cirrhosis), mural pleural lymphatic reflux disorders (such as cancerous lymphatic vessel obstruction), and chest injuries can cause pleural effusion, and the common clinical causes are as follows: 1. Leaky pleural effusion Congestive heart failure The pleural effusion caused by congestive heart failure, constrictive pericarditis, liver cirrhosis, superior vena cava syndrome, nephrotic syndrome, glomerulonephritis, dialysis, mucinous edema, etc. is often a leaky fluid. (2) Exudative pleural effusion (1) Pleural malignancy including primary mesothelioma and metastatic pleural tumor. (2) Infections of the chest and lung, such as tuberculosis and other bacterial, fungal, viral, and parasitic infections. (3) Connective tissue diseases such as systemic lupus erythematosus, polymyositis, scleroderma, and dry syndrome. (4) Lymphocyte abnormalities such as multiple myeloma, lymphoma. (5) Drug-related pleural diseases such as minoxidil, bromocriptine, dimethyl ergonovine, methotrexate, levodopa, etc. (6) Digestive system diseases such as viral hepatitis, liver abscess, pancreatitis, esophageal rupture, diaphragmatic hernia. (7) Others Hemothorax, celiac disease, uremia, endometriosis, radiation injury, post-myocardial infarction syndrome, etc.