RESUMEN
In this paper we present the results of a study about the diagnostic utility of Adenosine Deaminase (ADA) determination for diagnosing the tuberculous pleural effusion. We carried out this study in 71 patients who came to our Hospital and were diagnosed for pleural effusion. The ADA determination was made in sera and pleural effusion of all these patients. Also we determined how much of this ADA activity was linked to microsomes or not (soluble ADA), by ultracentrifugation as a separative method. Taking as a base the data obtained and using 43 U/l as cutoff point, the Diagnostic Sensitivity of ADA determined in pleural liquid calculated was 1. This means that all patients with tuberculous pleural effusions had ADA activities higher than 43 U/l in their pleural liquid. On the other hand, Diagnostic Specificity was of 0.83. This was due to the existence of 10 false positives: 2 malignancies, 3 empyemas, 1 postpneumonia, 1 secondary to thromboembolic pulmonary disease, 1 secondary to rheumatoid arthritis and 2 of unknown origin. Results obtained show the utility, with some limitations, of ADA determination in pleural liquid in order to diagnose tuberculous pleural effusions. Neither ADA determination in sera nor quantity of ADA linked to microsomes or solubles ADA in pleural liquid seem to have great clinical interest.