Role of pleural fluid cholesterol in differentiating transudative from exudative pleural effusion.

BACKGROUND: Pleural fluid cholesterol has been reported to be useful in distinguishing between transudative and exudative pleural effusion. However, the difference in lipid profile between tubercular and non-tubercular pleural effusion has not been studied. METHODS: The lipid profile of pleural fluid in 50 patients with exudative (25 tubercular and 25 non-tubercular) and 25 with transudative effusion was studied. The diagnosis was based on clinical criteria and/or a positive diagnosis from another site. RESULTS: The criteria that best identified an exudative pleural effusion were pleural fluid cholesterol > or = 60 mg/dl, pleural fluid to serum cholesterol ratio > or = 0.4, pleural fluid triglyceride > or = 40 mg/dl and pleural fluid to serum triglyceride ratio > or = 0.3. Pleural fluid cholesterol had a sensitivity of 88% and a specificity of 100% for exudates with an accuracy of 92%. Pleural fluid to serum cholesterol ratio had a sensitivity of 98% and a specificity of 84%. These results were superior to the criteria proposed by Light et al. (sensitivity 98% and specificity 80%). CONCLUSION: Pleural fluid cholesterol estimation is an effective and cost-efficient method of differentiating exudative from transudative pleural effusion. The lipid profile does not help in diagnosing tubercular effusion.