CEACAM5 and Pleural effusion: The mean concentrations of adenosine deaminase, carcinoembryonic antigen, and protein in the pleural effusions were 8.8 U/L (range: 0.2–21.8 U/L), 0.92 mg/mL (range: 0.4–1.8 mg/mL), and 29.3 g/dL (range: 16.4–45.2 g/dL), respectively.