Usefulness of pleural fluid ada level in differential diagnosis of exudative pleural effusion – a pilot study

Dharmveer Yadav, Pallavi Taparia, Sandhya Mishra and S.P Agnihotri

Pleural effusion is an abnormal collection of fluid in pleural space resulting from excess fluid production. It is a frequent manifestation of serious thoracic disease whose specific diagnosis is a challenging task. Pleural effusion can be due to Infectious, malignant, parapneumonic disease and tubercular or other causes. Accurate diagnosis of etiology of pleural effusion (PE) by clinical or radiological methods is difficult due to overlapping symptoms and microbiological test are time consuming. Thus, diagnostic efficiency of Pleural fluid Adenosine Deaminase PF ADA was analysed in this study specifically for tubercular pleural effusion. TB is a global health problem and therefore requires a method which is of short duration with acceptable sensitivity and specificity to diagnose it. The study aims to assess utility of Pleural fluid ADA as a routine biochemical test for diagnosis of exudative pleural effusion arising due to tubercular and other causes.

Material and Method The study involved 187 adult patients diagnosed with exudative pleural effusion and classified into 5 groups as follows:1 Malignant pleural effusion (MPE), 2 Chronic non-specific inflammation (CNI), 3 Parapneumonic pleural effusion (PPE), 4.Tubercular pleural effusion (TBPE) and 5. Others. After complete clinical evaluation, routine Pleural fluid analysis and ADA was analysed. Reciever Operating Characterstics (ROC) analysis established the cutoffs of ADA for discriminating between groups. 

Result and Discussion pleural fluid ADA was significantly higher in Tubercular effusion group (88.12± 35.9 U/L), followed by CNI group (73.41± 29.0 UL) than any others groups. Further, sensitivity and specificity of 94.1 and 69.4 % was obtained in Tubercular group at cut off 32.3 U/L. Though, at cut off 27.85 U/L PPE patients show 100% sensitivity but its specificity was much less i.e. 31.5%. The results show greater diagnostic accuracy of ADA in tuberculosis with acceptable Positive predictive value and Negative Predictive value. P F ADA is a simple, cost effective and useful in differential diagnosis of Tubercular pleural effusion where other cytological and biochemical test gives misleading results. This diagnostically effective in countries like India where large population lives in overcrowded and poorly ventilated areas and are thus highly prone to infectious diseases like Tuberculosis.

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