Role of pleural fluid interleukin-6, neutrophil-lymphocyte ratio, and monocyte-lymphocyte ratio in distinguishing tuberculous and malignant pleural effusions

Background: Pleural effusion is caused by various disease, including tuberculosis infection and malignancy. To determine the etiology, immunologic parameters are needed to distinguish tuberculous and malignant pleural effusions, including pleural fluid interleukin-6 (IL-6), neutrophil-lymphocyte ratio (NLR), and monocyte-lymphocyte ratio (MLR).Methods: This was a cross-sectional study, conducted at Sanglah General Hospital in Denpasar from March 2020 to September 2020. Pleural fluid IL-6 and leucocyte differential count were measured from subjects with tuberculous and malignant pleural effusions.Results: There were 22 tuberculous pleural effusion subjects with mean pleural fluid IL-6 9269.017±902.211 pg/ml, median (range) pleural fluid NLR 0.123 (0.044-9.449), and MLR 0.065 (0.044-0.355). There were 31 subjects with malignant pleural effusions, with mean pleural fluid IL-6 8212.146±2022.350 pg/ml, median pleural fluid NLR 0.189 (0.015-2.599), and MLR 0.065 (0.010-0.254). Pleural fluid IL-6 in tuberculous pleural effusions were significantly higher (p=0.014). With a pleural fluid IL-6 cut-off ≥9147.959 pg/ml, sensitivity of 63.6% and specificity of 64.5% were obtained. Pleural fluid NLR and MLR of the two groups were not significantly different (p=0.807 and p=0.116).Conclusions: Pleural fluid IL-6 in tuberculous pleural effusions is higher than malignant pleural effusions, with a cut-off of ≥9147.959 pg/ml, tuberculous pleural effusions can be diagnosed with sensitivity of 63.6% and specificity of 64.5%. There is no difference in pleural fluid NLR and MLR in tuberculous and malignant pleural effusions.