Light’s Criteria

Light’s Criteria Determination of transudate versus exudate source of pleural effusion Fluid is exudate if one of the following Light’s criteria is present 1.Effusion protein/serum protein ratio greater than 0.5 2.Effusion lactate dehydrogenase (LDH)/serum LDH ratio greater than 0.6 3.Effusion LDH level greater than two-thirds the upper limit of the laboratory’s reference range of serum LDH Exudative effusions Abdominal fluid: Abscess in tissues near lung, ascites, Meigs syndrome, pancreatitis Connective-tissue disease: Churg-Strauss disease, lupus, rheumatoid arthritis, Wegener granulomatosis Endocrine: Hypothyroidism, ovarian hyperstimulation Iatrogenic: Drug-induced, esophageal perforation, feeding tube in lung Infectious: Abscess in tissues near lung, bacterial pneumonia, fungal disease, parasites, tuberculosis Inflammatory: Acute respiratory distress syndrome (ARDS), asbestosis, pancreatitis, radiation, sarcoidosis, uremia Lymphatic abnormalities: Chylothorax, malignancy, lymphangiectasia Malignancy: Carcinoma, lymphoma, leukemia, mesothelioma, paraproteinemia Transudative effusions Atelectasis: Due to increased negative intrapleural pressure Cerebrospinal fluid (CSF) leak into pleural space: Thoracic spine injury, ventriculoperitoneal (VP) shunt dysfunction Heart failure Hepatic hydrothorax Hypoalbuminemia Iatrogenic: Misplaced catheter into lung Nephrotic syndrome Peritoneal dialysis Urinothorax: Due to obstructive uropathy Exceptions These are processes that typically cause exudative effusions, but may cause transudative effusions. Amyloidosis Chylothorax Constrictive pericarditis Hypothyroid pleural effusion Malignancy Pulmonary embolism Sarcoidosis Superior vena cava obstruction Trapped lung