Classification of exudate by each Light's criterion
| Laboratory | Pleural fluid to serum protein >0.5 | Pleural fluid to serum LDH >0.6 | Pleural fluid LDH is >2/3 the upper reference limit for serum LDH |
|---|---|---|---|
| A | 21 | 18 | 26 |
| B | 24 | 14 | 15 |
| C | 25 | 12 | 9 |
LDH, lactate dehydrogenase.