Transferrin Concentrations in Serum and Lower Respiratory Tract Fluid of Mechanically Ventilated Patients With COPD or ARDS

Transferrin serves as the primary iron transport protein in serum, but it also is present in the lower respiratory tract where it has antioxidant and antibacterial properties. Prior studies indicate that patients with respiratory failure (RF) due to ARDS have increased concentrations of transferrin in the lower respiratory tract, which is attributed to increased lung vascular permeability. It is unclear whether mechanical ventilation contributes to increased lung transferrin content in patients with ARDS, although mechanical ventilation may increase lung microvascular permeability. To assess whether mechanical ventilation in patients with RF due to causes other than ARDS is also associated with increased respiratory tract concentrations of transferrin, we compared transferrin concentrations in serum and lung lavage fluid obtained from 12 mechanically ventilated patients with RF attributable to COPD, 6 patients with ARDS, and 15 healthy volunteers. Serum transferrin concentrations in patients with RF due to COPD were variable, but mean concentrations were similar to those in control subjects (336 ± 58 vs 307 ± 9 [SE] mg/dL), whereas serum transferrin concentrations were decreased in patients with ARDS (182 ± 68 mg/dL; p