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Eur J Intern Med. 2010 Oct;21(5):419-23. doi: 10.1016/j.ejim.2010.03.011. Epub 2010 May 1.

Diagnostic performance of adenosine deaminase activity in pleural fluid: a single-center experience with over 2100 consecutive patients.

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Pleural Diseases Unit, Department of Internal Medicine, Arnau de Vilanova University Hospital, Institut de Recerca Biom├Ędica de Lleida, Avda. Alcalde Rovira Roure 80, Lleida, Spain.



To determine the diagnostic utility of adenosine deaminase (ADA) in a large series of pleural effusions of different etiologies.


A retrospective study of 2104 consecutive patients presenting with pleural effusion was carried out at a Spanish university hospital. ADA levels in pleural fluid were determined using a non-Giusti automatic kinetic assay, and a receiver operating characteristics curve analysis was applied to estimate their discriminative properties.


Pleural tuberculosis (TB) accounted for 221 (10.5%) effusions. Pleural fluid ADA >35U/L yielded 93% sensitivity, 90% specificity, a positive likelihood ratio (LR) of 10.05 and a negative LR of 0.07 for the diagnosis of TB among lymphocytic exudates. The ADA activity was significantly higher in neutrophil- (111.6U/L) than in lymphocyte-rich (62.4U/L; p=0.002) TB effusions. Overall, more than 40% of parapneumonics and half of lymphomatous effusions exceeded the cutoff set for TB. These were the only causes of ADA activity above 250U/L. When the prevalence of TB as a cause of exudative effusions is low (e.g., 1%), the estimated positive predictive value of the ADA test may be as low as 7%, although the negative predictive value remains high (99.9%).


Where available, pleural ADA should be routinely used to rule TB in or out in areas with moderate to high or low TB prevalence, respectively. A high ADA level is a characteristic not only of lymphocytic, but also of neutrophilic TB effusions. An extremely high ADA activity should raise suspicion of empyema or lymphoma.

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