Abstract

Background: Pleural effusion represents a common clinical manifestation of diverse pathological processes. Accurate differentiation between exudative and transudative effusions is essential for appropriate diagnostic workup and therapeutic management. While Light's criteria remain the gold standard, pleural fluid cholesterol has emerged as a promising alternative discriminatory parameter.
Objective: To evaluate the diagnostic accuracy of pleural fluid cholesterol in distinguishing exudative from transudative pleural effusions and to compare its performance with Light's criteria.
Methods: This prospective observational study was conducted at a tertiary care hospital over 18 months, enrolling 120 patients with pleural effusion of varying etiologies. Detailed clinical assessment, imaging studies, and biochemical analysis of paired pleural fluid and serum samples were performed. Pleural fluid was classified as exudative or transudative using Light's criteria as the reference standard. Diagnostic accuracy parameters including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for various pleural fluid cholesterol cutoff values.
Results: Of 120 patients (mean age 52.4±15.8 years, 65% male), 78 (65%) had exudative and 42 (35%) had transudative effusions. Using a pleural fluid cholesterol cutoff of 60 mg/dL, sensitivity was 89.7%, specificity 88.1%, PPV 92.1%, and NPV 84.1% for identifying exudates. At 45 mg/dL cutoff, sensitivity increased to 96.2% but specificity decreased to 78.6%. The area under the ROC curve for pleural fluid cholesterol was 0.94 (95% CI: 0.89-0.98). Pleural fluid cholesterol demonstrated comparable diagnostic accuracy to Light's criteria while requiring fewer biochemical parameters.
Conclusion: Pleural fluid cholesterol is a reliable, simple, and cost-effective single parameter for differentiating exudative from transudative pleural effusions, with diagnostic accuracy comparable to Light's criteria. A cutoff value of 60 mg/dL provides optimal balance between sensitivity and specificity in clinical practice.