Evaluation of Serum and Pleural Levels of Angiopoietin-1 and Angiopoietin- 2 in Children with Transudative and Exudative Pleural Effusions

Objective: Angiopoietins are involved in the pathogenesis of a variety of human diseases. We tried to evaluate the application of pleural and serum Angiopoietin-1 and 2 in categorizing pleural effusions (PEs) into exudates and transudates in children.
Methods: Pleural fluid (PF) and serum Angiopoietin (Ang)-1 and Ang-2 were measured in 80 children with PEs (40 transudative and 40 exudative) by using enzyme-linked immunosorbent assay.
Findings: PF Ang-2 levels were significantly higher in pleural exudates than in transudates (P 0.012). PF Ang-2 levels were significantly higher than serum Ang-2 levels in patients with pleural exudates and transudates (P<0.001). PF Ang-2 levels were higher in tuberculous than in nontuberculous pneumonic PEs and empyema (P=0.01). PF Ang-2 levels correlate with serum Ang-2 levels (P<0.003). PF Ang-1 levels were significantly lower than serum Ang-1 levels both in patients with exudates and those with transudates (P<0.001). Cutoff points of serum and PF Ang-2, differentiating between transudative and exudative effusions were 3ng/ml and 8ng/ml respectively. Predictive potentials of serum and PF Ang-2 cutoff points were: Sensitivity 90% and 95% respectively, specificity 92.50% and 97.50% respectively, positive predictive value 92.30% and 97.40% respectively and negative predictive value 90.20% and 95.10% respectively.
Conclusion: Ang-2 levels were elevated in exudative PEs and correlated with levels of markers of pleural inflammation and pleural vascular hyperpermeability. It could categorize PE to exudates and transudates with valuable discriminative properties. That was detected more obviously in pleural fluids than in serum.

Keywords
Pleural Effusions; Transudates; Exudates; Angiopoietin-1; Angiopoietin-2