Abstract: Objective To explore the diagnostic value of adenosine deaminase(ADA) in the tuberculous pleurisy. Methods One hundred and sixty patients with pleural effusion admitted in Beijing Chest Hospital, Capital Medical University from January 2012 to December 2013 were recruited. In which 130 cases were confirmed as tuberculous pleural effusion and 30 cases were confirmed as malignant pleural effusion. The ADA in pleural effusion(p) and serum(s) were detected simultaneously both in tuberculous pleural effusion(TPE) and malignant pleural effusion(MPE). The ratio of pADA and sADA was figured out. Statistical analysis were done by SPSS 19.0, P<0.05 is considered statistically significant.  Results （1）The pADA, sADA and pADA/sADA in TPE ((55.8±19.5) U/L,(19.6±8.8) U/L,(3.1±1.2), respectively) were significantly higher than those in MPE ((11.1±5.0) U/L,(11.0±5.7) U/L,(1.1±0.5), respectively), the difference is statistically significant(t=21.5, 5.6 and 12.8，P<0.001). (2) The TPE patients were divided into two groups by 55 years old. The pADA value ((49.0±22.6) U/L) in patients ≥55 years old was lower than that in patients <55 years old ((57.8±18.5) U/L), the difference is statistically significant (t=2.3,P<0.05). (3) When the cut-off was set as 30U/L for the diagnosis of TPE, its sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 95.4%(124/130), 96.7%(29/30), 99.2%(124/125) and 82.9%(29/35), respectively. (4) If the critical value of pADA/sADA was set as ≥1.8 in TPE diagnosis, its sensitivity, specificity, PPV, NPV was 89.2%(116/130), 93.3%(28/30), 98.3%(116/118), and 66.7%(28/42), respectively. Conclusion The cut-off set as 30 U/L for pleural effusion has a very high sensitivity and specificity for the diagnosis of TPE. The value of pADA/sADA set as≥1.8 is helpful to diagnose differentially TPE from MPE.

Key words: Tuberculosis, pleural, Adenosine deaminase, Pleural effusion