Diagnostic value of procalcitonin in pleural effusions

This study was to determine the diagnostic value of procalcitonin (PCT) in the differentiation of infectious and non-infectious causes of pleural effusion. From January 2005 to April 2005, we measured the PCT levels of pleural effusion from 76 patients using an immunoluminometric assay. The types of pleural infusions studied were para-pneumonic effusion (n = 26), empyema (n = 7), tuberculous pleurisy (n = 8), malignant pleural effusion (n = 25) and transudative pleural effusion (n = 8). The PCT levels were low in transudative pleural effusions (0.188 ± 0.077 ng/mL) and tuberculous pleurisy (0.130 ± 0.069 ng/mL), but high in empyema (5.147 ± 3.056 ng/mL), para-pneumonic effusion (1.091 ± 0.355 ng/mL), and malignant pleural effusion (0.241 ± 0.071 ng/mL). The receiver-operating characteristic curve analysis for an optimal discrimination between empyema and para-pneumonic effusion from non-para-pneumonic effusion could be performed at a cut-off point of 0.18 ng/mL with area under the curve of 0.776 (sensitivity: 69.7%, specificity: 72.1%). The correlation was found between pleural effusion PCT and serum PCT levels in 16 patients (r² = 0.967, p < 0.001). In conclusion, a high pleural effusion PCT level suggests the presence of empyema and para-pneumonic effusion.