Which statement is NOT a Light's criterion for exudative pleural effusion?

• A. Pleural fluid cholesterol concentration > 60 mg/dL
• B. Pleural LDH/serum LDH ratio > 0.6
• C. Pleural LDH > two-thirds ULN
• D. Pleural fluid protein/serum protein ratio > 0.5

Answer: (A)

Light's criteria define an exudative pleural effusion using three tests: the pleural fluid-to-serum protein ratio greater than 0.5, the pleural fluid-to-serum LDH ratio greater than 0.6, and the pleural fluid LDH level higher than two-thirds of the upper limit of normal for serum LDH. A pleural fluid cholesterol concentration is not part of Light's criteria, though higher cholesterol can be seen in some exudates for other reasons. Therefore, the statement about pleural fluid cholesterol > 60 mg/dL is not a Light's criterion, making it the correct choice. The other three statements align with Light's criteria.