Pleural fluid Adenosine deaminase activity – Can it be a diagnostic biomarker? VinayBharat

Aim: To evaluate pleural fluid Adenosine deaminase as the diagnostic marker for tubercular pleural disease. Patients and Methods:New patients (n=160) with pleural effusion were divided into tubercular (n=92) and non-tubercular (n=68) groups. Non-tubercular group was further divided into patients having exudative effusion (n=46) and patients having transudative effusion (n=22). Patients with exudative effusion included those with adenocarcinoma (n=21), non-tuberculous empyema (n=11), parapneumonic effusion: (n=9) and lymphomas (n=5) while patients having transudative effusion included those with congestive heart failure (n=13), cirrhosis of liver (n=6) and with nephrotic syndrome (n=3). Pleural fluid was aspirated from all patients and tested for ADA. Results: In tubercular group Mean ± SD of ADA value was 67.78 ± 37.39 and it ranged between 8.8 – 260.0; in non-tubercular group collectively it was 22.17 ± 15.11 and ranged between 6.0 – 102.0. The performance of ADA for diagnosis of tuberculous pleural effusions in regards to the 95% confidence intervals and cut-off levels above 40.0 IU/L resulted in 88.04% sensitivity, 91.12% specificity, 95.25% positive predictive value, 85.33% negative predictive value, 90.63% diagnostic accuracy, 14.7 positive likelihood ratio, 0.13 negative likelihood ratio and 11.78 diagnostic odds ratio. The prevalence of disease in the studied population was 57.5%. Conclusion: It is concluded that ADA estimation in pleural fluid is not only simple, inexpensive and rapid but also fairly specific and sensitive method for diagnosing tuberculous etiology in patients of pleural disease. ADA activity in the pleural fluid can be a diagnostic biomarker and for this reason ADA estimation in pleural fluid may find a place as a routine investigation.