Proteins, lactate dehydrogenase and adenosine deaminase levels in pleural fluid - useful markers for differentiating tuberculosis from lung cancer

Shaikh Mahmood., Syyeda Anees., Badar uz zama and Abbas Hyder

To evaluate the clinical and laboratory characteristics of pleural effusions in to tuberculosis (TB) or cancer (CA). A total of 385 patients with pleural effusion due to TB (n=175) or CA (n=112) were studied. The following parameters were analyzed: patient gender, age and pleural effusion characteristics (size, location, microscopic fluid aspect protein concentration, lactate dehydrogenase (DHL) and adenosine deaminase activity (ADA) and nucleated cell counts).



Key words:


Pleural effusion. Neoplasm. Tuberculosis. Carcinoma. Adenosine deaminase. Patients, Lactate dehydrogenase. Exudates, Transudate.


The objective of this study was to evaluate the utility of the determination of protein concentration, lactate dehydrogenase (DHL) and adenosine deaminase (ADA) level in pleural fluid for the differential diagnosis between tuberculous pleural effusion (TPE) and malignant pleural effusion (MPE). We retrospect tively reviewed the clinical records of 385 patients with pleural effusion and investigated their pleural protein concentration, DHL and ADA levels as determined by an auto analyzer (Micro Lab 300).   The study included patients with TPE (n=175), MPE (n=112), benign non-tuberculous pleural effusion (n=81), and pleural effusion of unknown etiology (n=17).  Although the protien concentration, DHL and ADA activity in pleural fluid can help in the diagnosis of TPE and MPE patients.


Fluid with higher protein (p < 0.001) levels predominated in effusions from the tuberculosis group (5.3 + 0.8 g/dL) when compared to the CA group (4.2 ± 1.0 g/dL), whereas DHL levels were more elevated in CA (1,177 ± 675 x 1,030 ± 788 IU; p = 0.003) than in TB. As expected, ADA activity was higher in the TB group (107.6 ± 44.2 X 30.6 ± 57.5 U/L; p < 0.001).


Our  results  demonstrate  that  in  lymphocytic  pleural exudate  obtained  from patients  with  clinical  and radiological evidence of tuberculosis, protein concentration, DHL and ADA were the parameters that better characterize these effusions. In the same way, when the clinical suspicion is malignancy, serous- hemorrhagic lymphocytic fluid should be submitted to oncotic cytology once this easy and inexpensive exam reaches a high diagnostic performance ( 80%). In this context, we suggest thoracocentesis with fluid biochemical and cytological examination as the first diagnostic approach for these patients.

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