RESUMO
PURPOSE: We studied the diagnostic value of cytokines, including vascular endothelial growth factor (VEGF), transforming growth factor-ß (TGF-ß), and interleukin-8 (IL-8), and the ratio of lactate dehydrogenase (LDH) to adenosine deaminase (ADA) in pleural fluid. METHODS: Prospective analysis of 44 inpatients or outpatients with pleural fluid, from December 2016 to March 2017 was conducted. RESULTS: We enrolled patients with malignant pleural effusion (MPE, N = 15), empyema (N = 11), parapneumonic effusion (PPE, N = 7), chronic renal failure (CRF)/chronic heart failure (CHF) (N = 7), and tuberculous pleural effusion (TBPE, N = 4). The pleural fluid values of IL-8 and VEGF were significantly higher in empyema patients than in CRF/CHF or PPE patients. In all patients, the pleural fluid VEGF and IL-8 values were significantly positively correlated (r = 0.405, p = 0.006; r = 0.474, p = 0.047, respectively). TGF-ß was elevated in patients with empyema, PPE, TBPE, and MPE. The pleural LDH-to-ADA ratio in patients with MPE or empyema/PPE was significantly higher than in patients with CRF/CHF or TBPE. LDH and ADA levels correlated significantly only in patients with MPE (r = 0.648, p = 0.009) and empyema/PPE (r = 0.978, p < 0.001). CONCLUSIONS: VEGF and IL-8 production in the pleural cavity appear to accelerate the progression of PPE to empyema, by enhancing vascular permeability associated with inflammation. Sequential sampling would be needed to confirm this. The pleural LDH/ADA ratio may be a useful diagnostic tool for discriminating between various pleural effusion etiologies.
