Light's criteria are used to differentiate between exudative and transudative pleural effusion by analyzing pleural fluid and serum. The criteria are as follows:
A pleural effusion is classified as exudative if at least one of the following conditions is met:
1. Pleural fluid protein/Serum protein ratio > 0.5
2. Pleural fluid lactate dehydrogenase (LDH)/Serum LDH ratio > 0.6
3. Pleural fluid LDH > two-thirds of the upper limit of normal (ULN) for serum LDH
If none of these criteria are met, the pleural effusion is classified as transudative.
Exudative pleural effusion |
Transudative pleural effusion |
1. Infection (Tuberculosis, 2. Malignancy 3. Others- |
1. Heart failure 2. Nephrotic syndrome 3. Cirrhosis |