Determination of tissue polypeptide-specific antigen in pleural fluid and serum from patients with pleural effusion

As a tool for differentiating malignant and benign pleural effusions, we evaluated the diagnostic value of the assay of tissue polypeptide-specific antigen (TPS) in pleural fluid and serum, and of the pleural fluid TPS/serum TPS ratio in patients with pleural effusion. We studied prospectively 147 consecutive patients who had pleural effusions: 43 malignant pleural effusions and 104 benign pleural effusions. TPS levels were measured by RIA. The sensitivity and specificity of these measurements were: TPS in pleural fluid (cutoff 20,000 U/L): 0.21 and 0.98; TPS in serum (cutoff 300 U/L): 0.31 and 0.96; pleural fluid TPSI serum TPS ratio (cutoff 1200): 0.07 and 0.99.

All these values enhanced the sensitivity of cytologic analysis of pleural fluid. However, we conclude that TPS assay in pleural fluid and serum, and the pleural fluid TPSI serum TPS ratio have limited diagnostic value in patients with pleural effusion.