Role of C-reactive protein in distinguishing between transudative and exudative pleural effusion

Introduction: Still there is no wide agreement regarding the efficacy of serum levels of C-reactive protein (CRPs), pleural fluid levels of CRP (CRPpf), and their ratio (CRPr) in distinguishing between transudative (Tr) and exudative (Ex) pleural effusion (PE). Most of the previous studies in this regard were on small cohorts. The role of CRPs and CRPpf gradient (CRPg) in distinguishing between TrPE and ExPE has not been previously reported. Aims: To assess the diagnostic efficacy of CRPs, CRPpf, CRPg, and CRPr in distinguishing between TPE and ExPE in a relatively large cohort with PE. Methods: The study population included 492 patients with PE; 210 with TrPE, and 282 with ExPE. Levels of CRPs and CRPpf were measured, and levels of CRPg and CRPr were calculated. Adequate statistical methods were used, including the ROC analysis. The values are presented as mean±SD. Results: Mean levels of CRPs, CRPpf, CRPg, and CRPr of the TrPEs were 11.3±5.7 mg/L, 4.6±2.8 mg/L, 6.7±3.9 mg/L, and 0.40±0.14 respectively, and for the ExPEs were 140.5±112.8 mg/L, 52.8±53.2 mg/L, 87.2±72.4 mg/L, and 0.37±0.15 respectively. Levels of CRPs, CRPpf, and CRPg were significantly higher in the ExPEs than in the TrPEs with p Conclusion: CRPs, CRPpf, and CRPg but not CRPr, are very much effective in distinguishing between TrPE and ExPE.