Discrimination of tuberculous from carcinomatous pleural effusion by biochemical markers: adenosine deaminase, lysozyme, fibronectin and carcinoembryonic antigen.

Abstract

We measured adenosine deaminase (ADA), lysozyme, fibronectin and carcinoembryonic antigen (CEA) in the pleural fluid of tuberculous and carcinomatous pleural effusion in order to discriminate these two groups. Tuberculous pleural effusion had significantly higher levels of ADA and lysozyme than did carcinomatous effusion. When ADA activity of more than 33 IU/l is considered, diagnostic tests of tuberculous effusions showed a sensitivity of 100%, specificity of 95% and accuracy of 96%. A pleural fluid/serum ADA ratio (pl-ADA/s-ADA) above 1.1 was found in 100% of tuberculous and in 53% of carcinomatous effusions (sensitivity 100%, specificity 47%, diagnostic accuracy 70%). A lysozyme level above 12 micrograms/ml, selected as the discriminating limit, was found in 100% of tuberculous and in 17% of carcinomatous effusions (sensitivity 100%, specificity 83%, diagnostic accuracy 88%). Pleural fluid/serum lysozyme ratio (PL/SL) was also valuable in the discrimination of these two groups. When the cut-off level of 1.2 was considered, diagnostic tests of tuberculous effusions showed a sensitivity of 100%, specificity of 88% and accuracy of 93%, respectively. The mean fibronectin concentration in pleural fluid with tuberculous effusion was significantly higher than that in carcinomatous effusion, but there was a marked overlap between these two groups. On the other hand, CEA was significantly higher in carcinomatous effusions than in tuberculous effusions. At a cut-off level of 5 ng/ml, 53% of patients with carcinomatous effusion showed elevated pleural fluid CEA levels, while none of the tuberculous effusion did (sensitivity 53%, specificity 100%, diagnostic accuracy 65%).(ABSTRACT TRUNCATED AT 250 WORDS)