The usefulness of pleural fluid presepsin, C-reactive protein, and procalcitonin in distinguishing different causes of pleural effusions.

Background: We aimed to determine the presepsin concentration in pleural fluid from patients with pleural effusions of different aetiologies and to compare its diagnostic value with that of pleural fluid C-reactive protein (CRP) and procalcitonin (PCT).
Methods: We enrolled 132 patients with pleural effusion who underwent diagnostic evaluation, and we classified them into six categories: empyema, parapneumonic effusion, tuberculous effusion, malignant effusion, paramalignant effusion, and transudate effusion. Additionally, all pleural effusions were categorised as infectious or non-infectious effusions.
Results: Receiver operating characteristic analysis was used to evaluate diagnostic performance. When diagnosing empyema, the marker with the highest sensitivity was pleural fluid presepsin (cut-off: 754 pg/mL; sensitivity: 90.9%, specificity: 74.4%) and that with the highest specificity was pleural fluid CRP (cut-off: 4.91 mg/dL; sensitivity: 63.6%, specificity: 89.3%). Pleural fluid PCT tended to be lower in patients with empyema than in those with parapneumonic effusion, but this was not useful for the diagnosis of empyema. When diagnosing infectious pleural effusion, a combination of pleural fluid CRP (cut-off: 2.59 mg/dL) and presepsin (cut-off: 680 pg/mL) produced the highest diagnostic accuracy (83.3%).
Conclusions: Pleural fluid presepsin was found at high levels in patients with empyema and parapneumonic effusion. This pattern closely resembles the previously reported pattern of pleural fluid CRP. Some combinations of pleural fluid inflammatory markers may be more clinically useful than these markers in isolation.