The effect of total thiol, native thiol and thiol disulfide levels in the differentiation of benign and malignant pleural effusion

Pleural effusion (PE) is the accumulation of fluid in the pleural space caused by many benign and malignant conditions. Pleural effusion is seen in most common diseases such as cancer, pneumonia and heart failure. The gold standard for the diagnosis of benign and malignant pleural effusion is video-assisted thoracoscopic surgery and pleural biopsy. But this is an invasive surgical procedure. Examination of pleural effusion in benign and malignant cases in terms of oxidant and antioxidant balance may contribute to the diagnosis. In this study, it was aimed to examine serum and pleural effusions in terms of antioxidant balance in order to differentiate malignant and benign pleural effusions. In this study, patients were divided into 2 groups as benign (n=18) and malignant (n=32) pleural effusions. Pleural fluid and serum samples were collected simultaneously from the patients. Total Thiol (TT), Native Thiol (NT) and Thiol Disulfide (D), Total Antioxidant Level (TAS), Total Oxidant Level (TOS), Oxidative Stress Index (OSI) levels, which are oxidative stress markers, were examined in the fluid and serum samples. Serum TT (364.44±135.85 µmol/L) and NT (169.94±63.25 µmol/L) levels in the benign group were decreased as TT ( 459.45±221.26 µmol/L) and NT (195.80±156.86 µmol/L) levels in the malignant group and D (97.25±44.42 µmol/L) levels in the benign group were increased as D (131.82±81.89 µmol/L) levels in the malign group. However, there was no significant difference PE fluid TT (385.96±189.56 µmol/L), NT (269.5±135.32 µmol/L), D (58.23±44.77 µmol/L) levels in the benign group compared to TT (372.96±174.79 µmol/L), NT (266.23±142.90 µmol/L), D (53.28±29.94 µmol/L) levels in the malign group. There were no significant differences between benign group and malignant group serum TAS (1.59±0.18 mmol/L; 1.48±0.27 mmol/L, respectively), TOS (2.77±1.67 µmol/L; 3.69±1, 64 µmol/L, respectively) and OSI (0.17±0.11; 0.26±0.13, respectively) levels and PE fluid TAS (1.82±0.37 mmol/L; 1.97±0.35 mmol/ L, respectively), TOS (34.98±22.55 µmol/L; 33.89±24.02 µmol/L, respectively) and OSI (2.01±1.51; 1.71±1.08 µmol/L, respectively) levels. As a result, we thought that there is no statistical difference between benign and malignant groups, it would not be appropriate to use these parameters in differential diagnosis yet, but it would be beneficial to repeat the study with more samples and additional parameters. Keywords: Pleural effusion, total thiol, native thiol and thiol disulfide.