Study objective: We sought a marker to differentiate tuberculous pleural effusions from nontuberculous pleural effusions, which otherwise can be difficult.
Patients: We studied 55 patients with pleural effusions, 20 (36%) with tuberculous pleuritis and 35 (64%) with a nontuberculous etiology.
Measurement and results: Pleural fluid levels of adenosine deaminase, interferon (INF)-γ, interleukin (IL)-12p40, IL-18, immunosuppressive acidic protein, and soluble IL-2 receptors were measured and were subjected to receiver operating characteristic analysis. INF-γ had the greatest sensitivity and specificity for tuberculous pleuritis among the six biological markers studied.
Conclusion: The determination of INF-γ levels in pleural fluid is the most informative in the diagnosis of tuberculous effusion.