Diagnostic Efficacy of Adenosine Deaminase Isoenzyme in Tuberculous Pl

Background : Tuberculosis is the most common cause of pleural effusion in Korea. But the differential diagnosis of pleural effusion is important because malignancy and pneumonia are also other common causes of pleural effusion. Adenosine deaminase (ADA) activity is used to differentiate tuberculous pleurisy from non-tuberculous pleural effusion. However, some cases of non-tuberculous effusion show increased activity of ADA. Therefore, this study is for evaluating diagnostic efficacy of the ADA isoenzyme activity in the diagnosis of tuberculous pleurisy. Methods : The activity of total ADA and ADA2 isoenzyme activity and ratio of ADA2/ADA in 293 patients with pleural effusion were measured. Then, it was compared to conventional and PCRhybridization methods for tuberculous pleurisy. Results : Total ADA and ADA2 isoenzyme activity in tuberculous pleurisy were 81.829.5 U/L and 67.023.2, respectively, which were significantly higher than non-tuberculous effusion (20.321.3 U/L and 12.59.0 U/L1). With a cut-off level of 45 U/L in total ADA activity and the ratio of ADA2/ADA 0.6 or greater, the sensitivity and specificity for tuberculous pleurisy were 92.1% and 98.8%, respectively. Conclusions : Total ADA and ADA isoenzyme activities are useful to differentiate tuberculous pleurisy from non-tuberculous pleural effusion compared to conventional methods. Especially, various combinations of the total ADA, the ADA2 isoenzyme activities, and the ratio of ADA2/total ADA show high diagnostic efficacy for tuberculous pleurisy.