Evaluation of ferritin, interleukin-6, interleukin-8 and tumor necrosis factor alpha in the differentiation of exudates and transudates in pleural effusions.

In an attempt to define diagnostic criteria for the differentiation of pleural exudates from transudates, we measured ferritin (FER), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha) in pleural effusions and blood serum in 84 consecutive patients with pleural effusions of various etiologies. Concentrations of FER, IL-8 and TNF-alpha were significantly higher in serum and pleural effusion in patients with exudates than in patients with transudates. Serum concentrations of IL-6 were not significantly increased in pleural exudate patients (9.78 +/- 17.12 fmol/L) compared to transudate patients (4.05 +/- 2.33 fmol/L), while significant differences were found between pleural exudates and transudates (p < 0.001). Increased levels of FER were found in serum and pleural effusion of cancer patients in comparison to non cancer patients (p < 0.001 and p < 0.001, respectively). Serum concentrations of IL-6, IL-8, and TNF-alpha were not significantly increased in cancer compared to non-cancer patients, while increased concentrations of IL-6 and IL-8 were found in pleural fluid of patients with cancer in comparison to non-cancer patients. Finally/ no statistically significant differences were found in serum and pleural TNF-alpha concentrations among patients with cancer and patients with non-cancer effusion. We conclude that FER, IL-6, IL-8 and TNF-alpha concentrations in pleural effusions are useful markers in differentiating exudates from transudates.