title: The role of serum surfactant protein D as a biomarker of exacerbation of chronic obstructive pulmonary disease.
abstract: BACKGROUND
  The exacerbation of chronic obstructive pulmonary disease (COPD) is a major factor for the high mortality associated with the disease. There is a paucity in the lung-specific biomarkers which diagnose these exacerbations. Surfactant protein D (SP-D) is a promising biomarker in predicting clinical outcomes for patients with COPD, is lung-specific and can be detected in serum. However, the profile in which serum concentrations of SP-D change during acute exacerbation is still unclear. This study aims to estimate and compare the concentrations of serum SP-D in patients with stable disease and during the exacerbation.
  
  
  METHODS
  A cross-sectional study was conducted which composed of apparently healthy individuals (n = 28), which included 14 smokers and 14 nonsmokers, patients with stable COPD (n = 28), and patients experiencing acute exacerbations (n = 28). Pulmonary functions were performed for all groups. Serum SP-D concentrations were measured using enzyme-linked immunosorbent assay (ELISA). These concentrations were compared by analysis of variance.
  
  
  RESULTS
  Serum SP-D levels were significantly elevated in patients with acute exacerbations (508.733 ± 102.813 ng/ml) compared to patients with stable COPD (337.916 ± 86.265 ng/ml) and healthy subjects (177.313 ± 46.998 ng/ml; p <  0.001). Serum SP-D levels correlated inversely with lung function parameters including FEV1%pred, FVC%pred and FEV1/FVC.
  
  
  CONCLUSIONS
  Serum SP-D levels are raised early on during acute exacerbations of COPD, which could be a potential early diagnostic biomarker for COPD exacerbations.
authors.affiliation: Department of Biochemistry and Microbiology, Faculty of Pharmacy, Damascus University, Damascus, Syria.
authors.forename: Alaa
authors.initials: A
authors.lastname: Zien Alaabden
authors.affiliation: Department of Internal Medicine, Chest Disease Section, Faculty of Medicine, Tishreen University, Lattakia, Syria.
authors.forename: Yousser
authors.initials: Y
authors.lastname: Mohammad
authors.affiliation: Department of Biochemistry and Microbiology, Faculty of Pharmacy, Damascus University, Damascus, Syria.
authors.forename: Sahar
authors.initials: S
authors.lastname: Fahoum
keywords: COPD diagnosis; COPD exacerbations; chronic obstructive pulmonary disease (COPD); serum biomarker; surfactant protein D (SP-D)