Aim and Background. To compare the diagnostic efficiency of adenosine deaminase, isoenzyme adenosine deaminase-2 and concentration of interferon-γ in patients with tuberculous pleural effusion.

  Materials and Methods. The prospective study was done on 114 patients who were divided into 3 groups: tuberculous, non-tuberculous infectious pleurisy, and malignant effusion. The adenosine deaminase, adenosine deaminase-2 and interferon-γ were analyzed by receiver operating characteristic curves.

Results. There was increase of all three markers in tuberculous pleural effusion but not in nontuberculous effusion. The cut-off values for adenosine deaminase, adenosine deaminase-2 and interferon-γ were 40, 26 U/l. and 299 pg/ml respectively. Adenosine deaminase, adenosine deaminase-2 activities were  significantly higher in tuberculous effusion than in malignant pleural effusion (more than 5 times) and in non-tuberculous infectious pleurisy (more than 4 times). The median of interferon-γ concentration in pleural fluid of tuberculous patients was 1514.2 pg/ml (931.2-2187.5 pg/ml) which was 10 times more than the median values of other groups of patients. There was no significant difference between patients with malignant effusion and those with non-tuberculous pleural effusion.

Conclusions. ADA and ADA2 in pleural is a marker for diagnostic of pleural effusion and all three markers had higher diagnostic yield for tuberculous effusion with 95% sensitivity.