Diagnostic value of carcinoembryonic antigen in exudative pleural effusions.

Elevated pleural fluid (PF) and plasma (PL) carcinoembryonic antigen (CEA) levels (ng/ml) were more frequently found with malignant than benign exudative effusions, but with a low true-positive rate for malignancy in general. Adenocarcinomatous effusions differed from other malignant and benign effusions in the frequency and degree of elevation of PF and PL CEA levels. A PF > 20 had a sensitivity of 91 percent and a specificity of 92 percent as a screening test for adenocarcinomatous effusions. A PF CEA > 55 or PL CEA > 10 were present only with malignancy and 98 percent specific for adenocarcinoma.