Background: The first step in the evaluation of patients with pleural effusion is to determine whether the effusion is a transudate or an exudate. Osteopontin (OPN) is a pleiotropic integrin-binding protein with many functions. We assessed pleural effusion and serum concentrations of OPN and C-reactive protein (CRP) in patients with different types of pleural effusions.
Methods: The current study comprised three groups: 20 patients with transudative effusion, 30 patients with malignant effusion and 30 patients with tuberculous effusion. OPN was analysed using a commercially available enzyme-linked immunosorbent assay kit.
Results: OPN effusion values were significantly higher in exudates (both malignant and tuberculous effusion cases) compared with transudative effusion. Also when compared separately, patients with tuberculous effusion and those with malignant effusion had a significantly higher fluid and OPN effusion/serum ratio than those with transudative effusion. Patients with tuberculous effusion had a significantly higher serum CRP effusion and effusion/serum ratio of CRP than those with malignant or transudative effusion.
Conclusion: OPN is significantly increased in exudative effusion compared with transudative ones. However, serum OPN and effusion/serum OPN ratio were not significantly different in patients with malignant from those with tuberculous effusions. The lack of difference in serum OPN and effusion/serum OPN ratio between patients with malignant and those with tuberculous effusion may be attributed to the heterogeneity of the malignant effusion group. Receiver-operating characteristic (ROC) curve analysis has shown that effusion/serum CRP ratio outperformed effusion/serum OPN ratio as a diagnostic marker for tuberculous pleural effusion.
