Exudative Pleural Effusion Calculation, Table
Lights Criteria Calculator
An online lights criteria and exudative pleural effusion calculation.
Protein Paramaters
LDH Parameters
Exudative Pleural Effusion
Lights criteria can be used to determine the type of a patients pleural effusion and thus its etiology.
Pitfalls
The following diseases typically are exudative effusions, but in certain cases may be transudative:
Amyloidosis
Trapped lung
Chylothorax
Constrictive pericarditis
Malignancy
Pulmonary embolism
Sarcoidosis
Lights criteria are more sensitive than specific for exudative effusions.
Transudate vs Exudate Table
Transudate is produced through pressure filtration without capillary injury while exudate is inflammatory fluid leaking between cells.
| Appearance | Clear | Cloudy |
| Specific gravity | < 1.012 | > 1.020 |
| Protein content | < 2.5 g/dL | > 2.9 g/dL |
| fluid protein/ serum protein | < 0.5 | > 0.5 |
| SAAG = Serum [albumin] - Effusion [albumin] | > 1.2 g/dL | < 1.2 g/dL |
| fluid LDH upper limit for serum | < 0.6 or < 2⁄3 | > 0.6 or > 2⁄3 |
| Cholesterol content | < 45 mg/dL | > 45 |
| Radiodensity on CT scan | 2 to 15 HU | 4 to 33 HU |