🫁 Light's Criteria (Pleural Effusion)
Classify a pleural effusion as exudate or transudate with Light's criteria.
Light's Criteria (Pleural Effusion)
Pleural fluid protein (g/dL)
Serum protein (g/dL)
Pleural fluid LDH (U/L)
Serum LDH (U/L)
Serum LDH upper limit of normal (U/L)
When to use
Direct the work-up of a pleural effusion.
How it works
Exudate if any: pleural/serum protein > 0.5, pleural/serum LDH > 0.6, or pleural LDH > ⅔ of the serum LDH upper limit of normal.
Key points
- Any one positive criterion = exudate.
- Very sensitive; can misclassify diuresed transudates.
- Use the albumin gradient if results are discordant with the clinical picture.
References
Decision support for licensed clinicians only; not a substitute for clinical judgement, diagnosis or local protocols.