Muhammad Ashraf, Muhammad Hussain, Kamran K Chima, Salman Ayyaz.
Diagnostic role of Adenosine Deaminase Level in Exudative Lymphocytic Pleural Effusions.
Pak J Chest Med Jan ;22(1):3-7.

Background: Exudative lymphocytic pleural effusion is common problem and tissue diagnosis is gold standard for the diagnosis but it is invasive procedure with complications. Raised ADA levels are observed in tuberculous effusion but definite cut off levels is lacking for our population. AIMS AND OBJECTIVES: To determine the diagnostic accuracy of pleural fluid ADA while comparing with closed pleural biopsy. STUDY DESIGN: It was a Cross-sectional (validation) study conducted in Pulmonology Department, SIMS/ Services Hospital Lahore, from December 15, 2013 to October 22, 2015. Materials & Methods: it is a prospective, non-randomized study performed in pulmonology Department, Services Hospital Lahore. 108 patients with lymphocytic exudative pleural Effusion were enrolled in the study. ADA levels were measured using commercially available ADA kit DIAZYME (Diazyme laboratories Poway, CA 92064, USA) on pleural fluid obtained by thoracocentesis and pleural biopsy specimen was taken by close pleural biopsy from each enrolled patient after informed consent. Results: Out of 108 patients 75 (69.4%) were males and 33 (30.6%) were females. Mean age was 45.21 +17.85 SD years. 69 (63.8%) cases were diagnosed as having Tuberculosis by pleural biopsy and/or AFB culture, 36 (33.33%) cases were diagnosed as malignant and 3 (2.7%) cases were inconclusive. In biopsy proven tuberculous pleural effusion (n=69), ADA level ranged from 30-128 IU/L with mean pleural fluid ADA level of 55.93 +14.12 IU/L and 68 patients had >40 IU/L. In non TB pleural effusion (NTPE) (n=39), ADA level ranged from 10-45 IU/L with mean pleural fluid ADA level of 21.35+ 12.65 IU/L. Only three patients had raised ADA levels >40. Taking pleural biopsy as gold standard and taking ADA level > 40 IU/L as cut off value, the sensitivity and specificity of pleural fluid ADA level in the diagnosis of TPE were 95.77% and 92.31%, respectively. Positive predictive value was 91.89%, negative predictive value was 97.29% and overall Diagnostic accuracy was 96.29%. Conclusion: ADA level in pleural fluid can be used as a diagnostic test in the workup for tuberculosis pleural effusion with sensitivity and specificity comparable to histopathology and/or culture for acid fast bacilli in pleural biopsy specimen.

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