Cureus. 2023 Aug 11;15(8):e43319. doi: 10.7759/cureus.43319. eCollection 2023 Aug.
Introduction While Light's criteria exhibit high sensitivity (98%) in detecting exudative pleural effusions, the capacity to rule out transudates is relatively limited. A previous study showed that approximately one-fifth of patients with congestive cardiac failure on diuretics also met the criteria for exudate. This study compares the diagnostic value of Light's criteria, the serum-effusion albumin gradient (SEAG) method, and pleural effusion glucose levels for accurately categorizing pleural effusion as transudate or exudate. Methodology We conducted this cross-sectional observational study in a tertiary care hospital in Ahmedabad, India. Two hundred patients with pleural effusion undergoing thoracentesis were included. Laboratory parameters measured in pleural fluid analysis included pleural fluid protein, pleural fluid lactate dehydrogenase (LDH), pleural fluid albumin, and pleural fluid glucose. Serum protein, serum LDH, and serum albumin were also collected. Mean values and standard deviations (SDs) were calculated for analysis. Results A significant difference was observed in the mean value of exudative and transudative effusions for each parameter (pleural fluid protein/serum fluid protein ratio, pleural fluid LDH/serum fluid LDH ratio, pleural fluid LDH, SEAG, and pleural fluid glucose) (P < 0.001). Light's criteria demonstrated the highest efficacy in diagnosing exudates (accuracy = 97.50%), while SEAG demonstrated the highest efficacy in diagnosing transudates (accuracy = 97.50%). Conclusion SEAG is an effective alternative diagnostic tool for identifying transudates misclassified by Light's criteria. Its use can contribute to prompt diagnosis and timely treatment of patients with pleural effusion, improving patient outcomes.