Adenosine deaminase activity in tuberculous pleural effusions: a diagnostic test.

The activity of adenosine deaminase (ADA) was investigated in pleural effusions from 10 patients with tuberculous pleurisy and 76 patients with pleural effusions of other aetiology. The ADA activity in the tuberculous patients was significantly higher than in the other groups, with the exception of those with empyema. Specificity (87%) and sensitivity (100%) of this test for tuberculosis is high when a reference limit of more than 53 U/l is taken.