Diagnostic utility of serum and pleural levels of adenosine deaminase 1–2, and interferon-γ in the diagnosis of pleural tuberculosis

BACKGROUND: To evaluate and compare the diagnostic efficiency of serum (s) and pleural (p) levels of adenosine deaminase (ADA)-1, ADA-2, total ADA, and interferon-gamma (IFN-γ) for the differential diagnosis of pleural tuberculosis (TB). METHODS: Clinical and analytic data of 93 consecutive patients with pleural effusions from May 2012 to February 2013 were prospectively evaluated. The study population included 43 pleural TB, 23 malignancies, and 27 other exudates. The median and interquartile range of ADA-1, ADA-2, total ADA, and IFN-γ were evaluated according to their underlying diseases. RESULTS: There were no significant differences in sADA-1 and sIFN-γ values among each group. pADA-1, pADA-2, total pADA, and pIFN-γ levels were significantly higher in patients with pleural TB than in other patients (p < 0.0001). As for pleural TB receiving operating characteristic (ROC) curves identified the following results. The best cut-off value for pADA-2 was 20.37 U/L and it yielded a sensitivity and specificity of 95.35% and 86%, respectively. Taking a cut-off value of 40.68 U/L for total pADA, the sensitivity and the specificity were found to be 88.37% and 88%, respectively. ROC curve identified 110 U/L as the best cut-off value for pμg/ml, while the sensitivity and the specificity were 74.42% and 68%, respectively. Finally, the best cut-off value for pADA-1 was 16.8 U/L and yielded a sensitivity and specificity of 69.77% and 68%, respectively. CONCLUSIONS: To distinguish pleural TB, pleural levels of ADA-2 have the highest sensitivity among the different diagnostic parameters and may find a place as routine investigation for early detection of TB in the future.