Criteria for Identifying Exudative Pleural Effusions
Test | Exudate | Sensitivity (%) | Specificity (%) |
|---|---|---|---|
Light’s criteria (≥ 1 of the following 3): | 98 | 77 | |
| ≥ 2/3 ULN for serum LDH | 66 | 100 |
| ≥ 0.5 | 91 | 89 |
| ≥ 0.6 | 93 | 82 |
Fluid total protein | ≥ 3 g/dL (30 g/L) | 90 | 90 |
Fluid cholesterol | ≥ 60 mg/dL (1.55 mmol/L) ≥ 43 mg/dL (1.11 mmol/L) | 54 75 | 92 80 |
Pleural fluid:serum cholesterol ratio | ≥ 0.3 | 89 | 71 |
Serum protein – pleural fluid protein† | ≤ 3.1 g/dL (31 g/L) | 87 | 92 |
* Correction for increase in LDH due to red blood cell lysis = measured LDH − 0.0012 × red blood cell count/mcL. | |||
† Preferred test for patients who are prescribed diuretics after development of effusion if Light’s exudative criteria are met, but none of the biochemical measurements are > 15% above the cutoff levels for Light’s criteria. | |||
LDH = lactate dehydrogenase; ULN = upper limit of normal. | |||
Data modified from Light RW: Clinical practice: Pleural effusion. N Engl J Med 346:1971–1977, 2002. doi:10.1056/NEJMcp010731 | |||