Biological markers in the diagnosis of tuberculous pleural effusion

Tuberculosis is one of the main etiologies to evoke in the context of lymphocyte pleurisy. However, diagnosis is difficult and is based on mycobacteriology that is not enough sensitive and time-consuming, or on histology that requires invasive biopsy gesture. This literature review, carried out from Medline, summarizes the main meta-analyzes, reviews, and originator publications in English on biomarkers, classic and more innovative, studied for the diagnosis of tuberculous pleurisy. Among the immuno-biochemical markers, interferon-γ (IFN-γ), isoenzyme of adenosine deaminase 2 (ADA2) and total adenosine deaminase (ADA) seem the most relevant with respective sensitivities of 89% (87-91), 97.2% (95 to 98.7) and 92% (90-93) and specificities of 97% (96-98), 94.2% (91.8 to 96) and 90% (89-91). About molecular biology, PCR Xpert MTB/RIF has a sensitivity of 46.4% (26.3 to 67.8), which is much higher than the direct examination, while providing rapid diagnostic confirmation, with a specificity of 99.1% (95.2 to 99.8), and a resistance to rifampicin screening. The release assay of interferon-γ (IGRA) is less effective with a sensitivity of 75% (69-81) and a specificity of 82% (75-88) in blood and a sensitivity of 80% (74-86%) and a specificity of 72% (64-80) in pleural fluid. Other biomarkers (including several cytokines) might have an interest but are still under evaluation. These innovative methods, particularly the determination of ADA and the use of PCR Xpert MTB/RIF should find their place in the diagnostic algorithm of TB pleurisy.