Pleural Interleukin-1β in Differentiating Transudates and Exudates: Comparative Analysis with Other Biochemical Parameters

Abstract

Background: The differential diagnosis of pleural effusion is a frequent clinical problem. The possible role of pleural fluid cytokines in discriminating transudates from exudates has not been studied adequately. Objective: The aim of this study was to evaluate the serum and pleural fluid levels of interleukin-1β (IL-1β) and to compare it with common biochemical parameters such as cholesterol (CHOL), lactate dehydrogenase (LDH), total protein and albumin. Methods: One hundred and six consecutive patients with pleural effusion were studied. IL-1β was measured simultaneously in blood and pleural fluid using a radioimmunoassay. Standard laboratory methods were employed for biochemical parameters. Results: Using ROC analysis, a pleural IL-1β cutoff level 18.16 fmol/ml had a sensitivity of 76.8%, a specificity of 58.3% and a positive predictive value (PPV) 86.3% in the discrimination of transudates vs. all exudates. Serum IL-1β levels were higher in the nonmalignant group but without statistical difference compared with transudate patients. In addition, a significant difference was found between serum IL-1β in the malignant group in comparison with those of the transudate group (p < 0.01), also IL-1β levels were significantly increased in exudate effusion when compared with transudate (p < 0.001, p < 0.05, respectively). CHOL values of ≧65 mg/dl had 92.7% sensitivity, and 100% specificity and PPV for both. Conclusions: The results of this study suggest that although IL-1β could be a marker with relatively good sensitivity and PPV for the differentiation of pleural effusion, the cost and time needed do not support its use as a routine laboratory test.