There are problems in the differential diagnosis of malignant
pleural effusion (MPE) and parapneumonic effusion (PPE). We investigated
the diagnostic value of levels of carcinoembryonic antigen (CEA) and C-reactive
protein (CRP) in the discrimination of MPE and PPE.
Materials and Methods: Twenty-eight patients with MPE and 21 patients with
PPE were assessed. CEA and CRP levels were measured in the pleural fluids.
Results: CEA levels in the pleural fluid were 55.03±102.96 ng/mL (0.4-387)
and 1.11±1.07 ng/mL (0.12-4.30) in patients with MPE and PPE, respectively.
The high levels of CEA in patients with MPE were statistically significant
(p<0.001). The sensitivity and specificity were 82% and 81%, respectively,
when the threshold value for CEA in the pleural fluid was set as 1.45 ng/
mL for the discrimination of MPE from PPE. CRP levels in the pleural fluid
were 28.75±23.20 mg/L (1.0-84.9) and 53.74±66.39 mg/L (3.10-248) for
patients with MPE and PPE, respectively. The level of CRP in patients with
PPE was not statistically significant (p=0.24). The sensitivity and specifity
were 61% and 58%, respectively, when the threshold value for CRP in the
pleural fluid was set as 28.35 mg/L for the discrimination of PPE from MPE.
Conclusion: CEA levels in the pleural fluid were significantly higher in patients
with MPE compared to those with PPE. However, the same did not
apply for CRP. According to this study, CEA levels in the pleural fluid may be
used as an adjunct test for the differential diagnosis of MPE and PPE but
CRP is not a good indicator for the discrimination between PPE and MPE.