Bottom line: Still considered gold standard for differentiating transudates and exudates, Light’s criteria has a 98% sensitivity and 83% specificity for exudates.
Summary: DynaMed summary on Pleural Effusion, Diagnostic Evaluation summarizes evidence in the section Differentiating Exudate from Transudate. Light’s criteria: ratio of pleural fluid protein to serum protein > 0.5; ratio of pleural fluid lactate dehydrogenase (LDH) to serum LDH > 0.6; pleural fluid LDH level > 2/3 upper limit of normal for serum LDH. DynaMed references:
Yataco JC, Dweik RA. Cleve Clin J Med. 2005 Oct;72(10):854-6, 858, 862-4. Pleural effusions: evaluation and management.
Review includes discussion of methods proposed to differentiate exudates and transudates. Compares in Table 3 (p. 858) Light’s criteria with newer proposed methods for differentiating transudates and exudates, none of which has demonstrated greater sensitivity and specificity. Cites the original prospective study (Ann Intern Med. 1972 Oct;77(4):507-13. Light RW)