Role of Pleural Fluid C-Reactive Protein in the Aetiological Diagnosis of Exudative Pleural Effusion

Abstract

Introduction: Pleural effusions, the result of the accumulation of fluid in the pleural space, are a major diagnostic problem due to its anatomical nature with no direct access. There is variation in management, depending on the pleural disease. The pleural effusion can either exhibit specific or nonspecific characteristics. Aim: To determine the clinical significance and diagnostic role of pleural fluid C-Reactive Protein (CRP) level in the aetiological diagnosis of exudative pleural effusion. Materials and Methods: This was a cross-sectional study performed during the study period of September 2013 to December 2014. A total of 53 Patients identified with pleural effusion were recruited in the study and pleural fluid was subjected for the measurement of CRP level. Pleural fluid CRP was assessed with CRP-Turbilatex-Quantitative turbidimetric immunoassay method which is based on the principle agglutination reaction. The data was subjected to statistical analysis using Epi info software version 3.4.3. The Receiver Operating Characteristic (ROC) curve was plotted to illustrate the diagnostic ability. The smallest cut-off value was the minimum observed test value minus 1, and the largest cut-off value was the maximum observed test value plus 1. All the other cut-off values were the averages of two consecutive ordered observed test values. Results: Among the 53 patients in the study, 42 had exudative effusions (79.20%) and 11 had transudative effusions (20.80%). The common cause of exudative effusion was tuberculosis 26 (61.90%), followed by 9 malignancy (21.40%) and 7 parapneumonic effusion (16.70%). In our study, the pleural fluid CRP was statistically significant (p<0.001) marker to differentiate exudative effusions with CRP-value <30 suggestive of malignancy, CRP-value 30-50 mg/L suggestive of tuberculosis and CRP-value >70 mg/L suggestive of parapneumonic effusions. Conclusion: Determination of pleural fluid CRP is a useful diagnostic marker for differentiating exudative and transudative effusions. Also, Pleural fluid CRP is a statistically significant marker in differentiating tubercular effusions from nontubercular exudative effusions.