Lights Criteria for Pleural Effusion Calculator

Lights Criteria for Pleural Effusion Explanation and Clinical Context Lights Criteria is a well established diagnostic framework used to differentiate exudative pleural effusion from transudative pleural effusion based on biochemical comparison of pleural fluid and serum. Exudative effusion indicates increased capillary permeability usually due to inflammatory or malignant processes while transudative effusion occurs because of hydrostatic or oncotic pressure imbalance such as in heart failure or hepatic cirrhosis. The criteria classify an effusion as exudative when at least one of three conditions is present which include a pleural to serum protein ratio greater than zero point five a pleural to serum LDH ratio greater than zero point six or pleural LDH level greater than two thirds of the serum LDH upper normal limit.

Clinical interpretation guides subsequent diagnostic steps such as evaluation for infection malignancy pulmonary embolism or autoimmune disease and helps avoid unnecessary procedures in cases where a transudative process is more likely.