Role of C-Reactive Protein as a marker for discrimination of Exudative and Transudative Pleural Effusion

Abstract

Background: Pleural effusion is a common clinical presentation that demands to be differentiated into exudative and transudative varieties for appropriate diagnosis and treatment. Though Light's criteria are the gold standard for diagnosis, they also have their limitations, particularly in specific clinical contexts. C-reactive protein (CRP), an acute-phase reactant, has been proposed as a possible biomarker here. Objective: To evaluate the diagnostic utility of pleural fluid CRP in distinguishing between exudative and transudative pleural effusions. Methodology: This cross-sectional study comprised 88 patients with radiologically proven pleural effusion in Liaquat National Hospital, Karachi. Pleural and serum samples were subjected to biochemical parameters such as CRP. Patients were divided into two groups; as exudative group (54) and transudative group (34) based on Light's criteria, and CRP values between both groups were compared. Results: Mean pleural fluid CRP concentrations were much greater in exudative effusions (12.7 ± 35.4 mg/dL) compared to transudative effusions (3.4 ± 4.1 mg/dL; p < 0.001). CRP was positive in 94.4% of cases with exudative effusions and 32.3% of cases with transudative effusions. The results indicate that pleural CRP is a good biomarker in distinguishing the type of pleural effusion. Conclusion: Pleural fluid CRP is a sensitive, widely available, and inexpensive marker for differentiating exudative from transudative effusions. Used with Light's criteria and clinical experience, it improves diagnostic accuracy and allows early and proper management.