Diagnostic value of procalcitonin and C-reactive protein in differentiation of pleural effusions

Background: Malignancies are a common and important causes of exudative pleural effusions. Several tumor markers have been studied because the pleural fluid cytology and pleural biopsy specimens do not provide a diagnosis in a high percentage of malignant effusions. In an attempt to overcome this limitation, procalcitonin and C-reactive protein (CRP) in pleural effusions and serum, which are known to be inflammation markers, were measured to determine if they can differentiate an exudate from trasndate as well as the diverse causes of exudative pleural effusion. Methods: 178 consecutive patients with pleural effusion (malignant 57, tuberculous 51, parapneumonic 31, empyema 5, miscellaneous benign 7, transudative 27)were studied prospectively. The standard parameters of pleural effusion and measured serum and pleural procalcitonin were examined using in immunoluminometric assay. The level of CRP in serum and pleural fluid was determined by turbidimetric immunoassay. Results: The pleural procalcitonin levels in the exudate were significantly higher than those in the transudate, 0.81±3.09 ng/mL and 0.12±0.12 ng/mL, respectively (p=0.007). The pleural CRP levels were significantly higher in the exudate than the transudate, 2.83±3.31 mg/dL and 0.74±0.67 mg/dL, respectively (p<0.001). The pleural procalcitonin levels in the benign effusion were significantly higher than those in the malignant effusion, 1.15±3.82 ng/mL and 0.25±0.92 ng/mL, respectively (p=0.032). The pleural CRP levels were significantly higher in the benign effusion than in the malignant effusion, 3.68±3.78 mg/dL and 1.42±1.54 mg/dL, respectively (p<0.001). The pleural procalcitonin levels in the non-tuberculous effusion were significantly higher than those in the tuberculous effusion, 1.16±3.75 ng/mL and 0.13±0.37 ng/mL, respectively (p=0.008). Conclusion: Measuring the level of procalcitonin and CRP in the pleural fluid is helpful for differentiating between transudates and exudates. In addition, it is useful for differentiating between benign and malignant pleural effusions.