Tumour necrosis factor alpha in the diagnostic assessment of pleural effusion

We investigated the role of tumour necrosis factor-alpha (TNF) in the evalu ation of pleural effusion aetiology. Using a commercially-available ELISA k it, concentrations of TNF were measured in the serum and pleural fluid of p atients with malignant effusions (n = 19), uncomplicated parapneumonic effu sions (n = 13), and exudative (n = 13) and transudative (n = 13) effusions due to congestive heart failure (CHFex and CHFtr, respectively). Serum TNF did not differ significantly between the four groups (p > 0.05). In the gro up with malignancy, pleural fluid TNF was significantly higher than in the other groups (p < 0.001), which were not significant different from each ot her (p > 0.05). However, a considerable overlap between all four groups was found. Pleural fluid TNF was significantly higher than serum TNF in the ma lignant and the uncomplicated parapneumonic groups (p < 0.001), and there w as a significant positive correlation between serum TNF and pleural fluid T NF in the group with uncomplicated parapneumonic effusion (r = 0.7, p < 0.0 05), in the group with CHFex (r = 0.54, p < 0.01), and in the group with CH Ftr (r = 0.8, p < 0.005), but not in the group with malignancy. Pleural flu id TNF:serum TNF (TNF ratio) was significantly higher in the malignancy gro up than in the other groups (p < 0.001); no significant difference was foun d between the other three groups (p > 0.05). At an optimal cut-off point of 2.0 for TNF ratio, determined by ROC analysis for discrimination between m alignant and nonmalignant groups, sensitivity was 84%, specificity 90%, and total accuracy 88% (p < 0.0001). TNF ratio might be helpful in the diagnos tic assessment of exudative pleural effusion.