Abstract: Objective To study the diagnostic value of pleural effusions protein electrophoresis and Adenosine Deaminase(ADA) in differentiating tuberculosis from malignant pleural effusion.Methods Thirty-six patients with tuberculous pleuritis and thirty-eight patients with malignant pleural effusion were examined.Protein electrophoresis and ADA of pleural fluid were measured by SEBIA HYDRASYS and colorimetry respectively.Results In tuberculosis and malignant pleural effusion,the level of α₁ global protein were4.32±1.35 and 3.41±0.97(P＜0.05),α₂ global protein were 8.98±1.50 and 6.01±1.53(P＜0.000),the ratio of α₂ global protein and album were 0.15±0.03 and 0.09±0.03(P＜0.000),and ADA were 71.35±24.00 and 31.21±11.90(P＜0.000).According to receiver operating characteristic curve(ROC),the sensitivity,specificity and accuracy of the ratio of α₂ global protein and album for diagnosing tuberculosis pleural effusion were 76%,89%,and 83% respectively.And the sensitivity,specificity and accuracy of ADA were 82%,78% and 80% respectively.The sensitivity,specificity and accuracy were 88%,100% and 94% when the two Methods were combined.Conclusion (1) The levels of α₁ global protein,α₂ global protein,the ratio of α₂ global protein and album,and ADA in tuberculosis pleural effusion were higher than that in malignant pleural effusion(P＜0.05).(2) Combining the ratio of α₂ global protein and album with ADA can raise the sensitivity,specificity and accuracy for diagnosing tuberculosis pleural effusion.

Key words: Pleural effusion, Protein electrophoresis, Adenosine deaminase