Diagnostic Value of Interleukin 21 and Carcinoembryonic Antigen Levels in Malignant Pleural Effusions

The aim of this study was to evaluate the diagnostic value of interleukin 21(IL-21) and carcinoembryonicantigen (CEA) in tuberculous pleural effusions (TPEs) and malignant pleural effusions (MPEs). Pleuraleffusion samples from 103 patients were classified on the basis of diagnosis as TPE (n=51) and MPE (n=52). Theconcentration of IL-21 was determined by ELISA. Lactate dehydrogenase (LDH), adenosine dehydrogenase(ADA) and CEA levels were also determined in all patients. A significant difference was observed in the levelsof ADA and CEA (P<0.01), but not in the levels of LDH (P>0.05) between TPE and MPE. The concentration ofIL-21 in MPE was significantly higher compared to TPE (P<0.01). With a threshold value of 4.32 pg/ml, IL-21had a sensitivity of 76.9% (40/52) and a specificity of 80.4% (41/51). Combined detection of IL-21 and CEAhad a sensitivity of 69.2% (36/52) and a specificity of 92.2% (47/51). These two markers can contribute to thedifferential diagnosis of MPEs.