Razi Journal of Medical Sciences

    Background & Aim: Adenosine deminase(ADA) can be used in the diagnosis of tuberculous pleural effusions. In countries with high prevalence of tuberculous pleural effusions, specificity and sensitivity for ADA test is high, therefore it is an integral part of a diagnostic workup of lymphocyte-rich exudative body fluids, and it is a cheap and economically cost-effective test. No study has been done on utilizing ADA test in the diagnosis of different lymphocytic pleural effusions in Iran. The present study was undertaken to determine the diagnostic value of ADA enzyme in the diagnosis of different lymphocytic pleural effusions and compare the results with pleural culture and biopsy. Patients & Methods: Sixty-five lymphocytic pleural fluid samples(lymphocyte count>50%) were analyzed which included 25 pleural effusions due to tuberculosis, 13 parapneumonic effusions, 17 malignant effusions, 5 CHF effusions, 13 effusions due to PTE and 2 post coronary artery bypass grafting(CABG) effusions. The results were analyzed by Pearson chi-square test. Results: ADA level reached a diagnostic cut-off for tuberculosis(45 u/l) in 22 cases. Also, this result was observed in 2 patients with malignancy and 2 patients with pneumonia. In other patients, this level was below 45U/L. The sensitivity and specificity of this test in the diagnosis of tuberculous pleural effusions was 88% and 90% respectively. Pearson chi-square test was utilized to demonstrate the significant difference in ADA test positivity in the tuberculous and nontuberculous pleural effusions and P<0.005 was obtained. Conclusions: ADA levels in nontuberculous lymphocytic effusions seldom exceed the diagnostic cut-off for TB(45 U/L), and according to the Pearson chi-square test, the difference in the positiveness of ADA test in the tuberculous and nontuberculous pleural effusions is significant. Therefore, this test can be valuable in the diagnosis of tuberculous pleural effusions.