Tumour Necrosis Factor-α in Comparison to Adenosine Deaminase in Tuberculous Pleuritis

Abstract

Background: Adenosine deaminase (ADA) is already used for the differential diagnosis of tuberculosis pleurisy. Tumour necrosis factor-α (TNF) is another marker which has been investigated for this purpose. Objective: We evaluated the diagnostic value of pleural fluid and serum TNF concentrations in tuberculous pleuritis and compared them to ADA. Methods: Sixty-two patients (24 tuberculous pleuritis, 38 non-tuberculous pleuritis) with exudative pleurisy were included. Serum and pleural fluid TNF concentrations were determined in all patients and ADA activity in 54 patients. Pleural fluid TNF concentrations and pleural fluid/serum TNF were compared to pleural fluid ADA activity and pleural fluid/serum ADA. Results: When the tuberculous and non-tuberculous groups were compared, pleural fluid TNF concentrations (65.4 ± 136.9 pg/ml vs. 54.5 ± 144.2 pg/ml, respectively; p < 0.001), pleural fluid ADA activity (74.2 ± 33.3 U/l vs. 23 ± 16.3 U/l; p < 0.0001), pleural fluid/serum TNF (2.55 ± 5.23 vs. 0.26 ± 0.2; p < 0.001) and pleural fluid/serum ADA (4.58 ± 8.14 vs. 1.15 ± 0.7; p < 0.0001) were significantly higher in the tuberculous group. When cut-off points were assessed, 8 pg/ml and 40 U/l were found for pleural fluid TNF concentrations and pleural fluid ADA activity, respectively. Sensitivity, specificity, area under the curve were 87.5%, 76.3%, 0.772 for pleural fluid TNF concentrations and 90.9%, 89.5%, 0.952 for pleural fluid ADA activity, respectively; the difference between these areas under the curves was significant (p < 0.05). Conclusions: Pleural fluid TNF levels and pleural fluid/serum TNF were higher in tuberculous effusions than in other exudates, but their diagnostic value appears to be poorer than that of ADA.