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Background: Pleural tuberculosis (TB) remains difficult to diagnose despite numerous diagnostic tools. Recently, in vitro interferon (IFN)-gamma-based assays have been introduced in the diagnosis of latent TB, but these techniques have not been established in the diagnosis of active TB disease, including pleural TB., Objectives: It was the aim of this study to assess the accuracy of the commercially available QuantiFERON TB Gold assay and adapted variants of the assay, using pleural fluid or isolated pleural fluid cells for the diagnosis of pleural TB., Methods: We recruited 66 consecutive patients with a pleural effusion of unknown cause presenting at a tertiary academic health care centre in Cape Town, South Africa, a high prevalence area of TB. Blood and pleural fluid were collected at presentation for IFN-gamma assays and the results evaluated for diagnostic accuracy., Results: The clinical diagnosis was TB in 30 (46%), malignancy in 20 (30%), parapneumonic effusion/empyema in 8 (12%) and effusion due to other causes in 8 patients (12%). Ex vivo pleural fluid IFN-gamma levels accurately identified TB in all patients and were superior to the QuantiFERON In Tube assay using blood and pleural fluid (73 and 57% sensitivity, with 71 and 87% specificity, respectively) and the QuantiFERON Gold assay applied to isolated pleural fluid cells (100% sensitivity and 67% specificity)., Conclusion: The ex vivo pleural fluid interferon-gamma level is an accurate marker for the diagnosis of pleural TB, and the QuantiFERON TB Gold assay performed with peripheral blood or adapted for pleural fluid cells does not add diagnostic value., (Copyright 2008 S. Karger AG, Basel.)

Background: C-reactive protein (CRP) pleural fluid levels have been found to be higher in tuberculosis and parapneumonic effusions than in other causes of pleural effusion., Objective: The aim of this study was to analyze whether CRP (a simple and inexpensive test) may be a diagnostic aid for tuberculosis in lymphocytic pleural effusions., Methods: One hundred and forty-four patients with a lymphocytic pleural effusion (more than 50% lymphocytes in the differential white blood cell count) were included. The patients were 93 men (65%) and 51 women (35%), aged 64 +/- 18 years (mean +/- SD). The diagnoses were as follows: tuberculosis, 20; pleural effusion associated with malignancy, 69; transudates, 38; other benign exudates, 17., Results: The CRP pleural fluid level was higher in tuberculous pleuritis (54 +/- 24 mg/l) than in lymphocytic effusions of other origin (21 +/- 16 mg/l; p < 0.001). High CRP levels (>or=50 mg/l) have a high specificity for tuberculosis (95%), and low levels (<30 mg/l) have a high sensitivity (95%) for excluding disease., Conclusions: CRP pleural fluid level determination is useful in the diagnostic workup of lymphocytic pleural effusions. High CRP levels are very suggestive of tuberculous pleuritis, and low CRP levels make this diagnosis unlikely., (Copyright (c) 2005 S. Karger AG, Basel.)

Lactic acid (LA) concentrations in the pleural fluid of 75 patients were determined by the Monotest Lactate Kit (MLK). Lactic acid values in 18 cases of bacterial or tuberculous pleural infection were strikingly higher (mean 81 mg%, range 45-200 mg%), than in 42 cases with pleural effusion due to congestive heart failure, hepatic cirrhosis, nephrosis, trauma, and systemic lupus erythematosus (SLE; mean 19 mg%, range 6-47 mg/). High levels of LA were also found in the pleural fluid of 15 patients with malignancy of pleural cavity. Determination of LA can be an additional rapid tool in the differentiation between bacterial pleural inflammation and pleural effusion of various forms except in cases with malignancy of the pleural cavity.