The Role of Pleural Fluid C-Reactive Protein in the Etiological Diagnosis of Pleural Effusion

Sakthivel N, Saritha Narayanan K

Abstract: Background: Differentiating the etiology of pleural effusion is crucial for management. Pleural fluid C-Reactive Protein (CRP) is a potential biomarker for this purpose. Objectives: To evaluate the diagnostic utility of pleural fluid CRP in distinguishing exudative from transudative effusions and in categorizing causes of exudative effusions. Methods: A cross-sectional study was conducted on 150 patients with pleural effusion. Pleural fluid analysis, including CRP, biochemical tests, cytology, and microbiology, was performed. Effusions were classified using Light's criteria. Statistical analysis was done using SPSS version 17. Results: A pleural fluid CRP cut-off of 3.31 mg/dL differentiated exudates from transudates with 96.3% sensitivity and 72.1% specificity. Parapneumonic effusions had the highest CRP levels (mean 102.99 mg/dL), followed by tuberculous (52.39 mg/dL) and malignant effusions (22.97 mg/dL). A CRP cut-off of 47.4 mg/dL differentiated parapneumonic from tuberculous effusions (sensitivity 87.5%, specificity 92.5%), and 49.2 mg/dL differentiated parapneumonic from malignant effusions (sensitivity 75%, specificity 85.7%). Conclusion: Pleural fluid CRP is a valuable, inexpensive, and readily available diagnostic tool that aids significantly in differentiating exudative from transudative effusions and in characterizing the etiology of exudative effusions.

Keywords: Pleural Effusion, C-Reactive Protein (CRP), Exudate, Transudate, Diagnosis, Biomarker

How to Cite?: Sakthivel N, Saritha Narayanan K, "The Role of Pleural Fluid C-Reactive Protein in the Etiological Diagnosis of Pleural Effusion", Volume 15 Issue 1, January 2026, International Journal of Science and Research (IJSR), Pages: 504-506, https://www.ijsr.net/getabstract.php?paperid=SR26107095332, DOI: https://dx.doi.org/10.21275/SR26107095332