The diagnostic role of pentraxin-3 in the differential diagnosis of pleural effusions

Background/aim: Discrimination of pleural effusion etiology is not always easy in clinical practice. Pentraxin-3 (PTX-3) is a new acute-phase protein. The aim of this study was to investigate the role of PTX-3 in the differential diagnosis of pleural effusions. Materials and methods: This prospective study enrolled all consecutive patients from two tertiary hospitals who underwent diagnostic or therapeutic thoracentesis. In a cohort of 149 subjects with pleural effusion, including transudates and malignant (MPE), tuberculous (TPE), and parapneumonic effusion (PPE), serum and pleural effusion PTX-3 concentration measurements were performed using ELISA. Serum and pleural effusion protein, lactate dehydrogenase, C-reactive protein (CRP), and adenosine deaminase levels were also assessed. Results: Of these patients, 34 had transudates, 29 had PPE, 63 had MPE, and 23 had TPE. There was a weak correlation between pleural effusion PTX-3 level and serum CRP (I ? <0.01). There was a significant difference in pleural PTX-3 levels between the exudative effusion groups (P <0.01). The median pleural effusion PTX-3 was significantly higher in patients with PPE (11.2 ng/mL, 2-17.8) than MPE (4.7 ng/mL, 1.8-13.9) and TPE (3.1 ng/mL, 2.0-4.1). At a cut-off point of 5.89 ng/mL, PTX-3 had the best discriminatory power for PPE versus other exudative effusions (sensitivity: 86.2%, specificity: 87.7%). The exudative effusion group had a significantly different pleural effusion/serum PTX-3 ratio (p = 0.03). Conclusion: PTX-3 concentration in pleural effusion was elevated without a significant correlation with serum PTX-3 in PPE. These results may suggest that PTX-3 is a local acute-phase reactant and may allow discrimination of PPE from other exudative effusions.