Diagnostic Accuracy of Pleural Fluid Cholesterol Levels in Differentiating Between Exudative and Transudative Pleural Effusions

Objective: To determine the utility of pleural fluid cholesterol levels in differentiating between exudative and transudative pleural effusions. Study Design: Cross-sectional analytical study. Place and Duration of Study: Department of Pulmonology, Combined Military Hospital, Peshawar Pakistan, from Sep to Dec 2021. Methodology: All patients aged less than 18 years, with pleural effusion confirmed on chest ultrasound, were included in our study. Patients with International Normalized Ratio >1.5, patients who were already under treatment for pleural effusion, patients on diuretics for more than 48 hours and patients not willing to participate in the study, were excluded. Light’s Criteria was used to label effusions as either exudates or transudates. Pleural fluid cholesterol ≥1.2mmol/L was considered as exudate. Results: Our study included a total of 78 patients, aged 52±21.27 years. Majority 63(80.7%) were males and most 51(65.4%) patients had exudative pleural effusion, while 27(34.6%) had transudative pleural effusion, as per Light’s Criteria. Out of 51 patients with exudative pleural effusion by Light’s Criteria, 41 had exudative pleural effusion on the basis of fluid cholesterol levels where mean pleural fluid cholesterol levels were 2.0±0.93 mmol/L and 1.04±2.32 mmol/L in exudative and transudative pleural effusions, respectively (p=0.01). Pleural fluid cholesterol levels of more than 1.2mmol/L had a diagnostic accuracy of 82%, sensitivity of 80% and specificity of 93% while the Positive Predictive Value was 95% and the Negative Predictive Value was 71%. Conclusion: Pleural fluid cholesterol levels of more than 1.2mmol/L can reliably differentiate between exudative and transudative pleural effusions.