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

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%.