title: Serum Procalcitonin for Differential Diagnosis of Acute Exacerbation and Bacterial Pneumonia in Patients With Interstitial Lung Disease.
abstract: BACKGROUND
  Acute exacerbation and bacterial pneumonia are major life-threatening conditions in patients with interstitial lung disease (ILD). The rapid recognition of these 2 different conditions is important for their proper treatment. An elevated procalcitonin (PCT) level is commonly detected in patients with bacterial infections. This study assessed the usefulness of the serum PCT level as a biomarker for the differential diagnosis of acute exacerbation and bacterial pneumonia in patients with ILD.
  
  
  METHODS
  In this prospective observational study, we enrolled patients with ILD who had experienced recently progressive dyspnea and exhibited new infiltrations on chest radiographs. We classified these patients into an acute exacerbation group and a bacterial pneumonia group and compared their baseline characteristics and laboratory parameters, including the PCT level.
  
  
  RESULTS
  Of 21 patients with ILD, 9 patients had bacterial pneumonia. Both the groups showed similar baseline characteristics. The bacterial pneumonia group demonstrated a high PCT level. The PCT level in the acute exacerbation group was significantly lower than that in the bacterial pneumonia group (0.05 versus 0.91ng/mL, respectively; P < 0.001). Other parameters, such as the C-reactive protein level, leukocyte count and body temperature, were also lower in the acute exacerbation group. At a cutoff value of 0.1ng/mL, the sensitivity, specificity and negative predictive values of the serum PCT level were 88.9%, 100.0% and 92.3%, respectively.
  
  
  CONCLUSIONS
  These findings suggest that the serum PCT level is useful in the differential diagnosis of acute exacerbation and bacterial pneumonia in patients with ILD.
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Jae Kyeom
authors.initials: JK
authors.lastname: Sim
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Jee Youn
authors.initials: JY
authors.lastname: Oh
authors.affiliation: Division of Respiratory and Critical Care Medicine, Department of Internal Medicine, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Eun Joo
authors.initials: EJ
authors.lastname: Lee
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Gyu Young
authors.initials: GY
authors.lastname: Hur
authors.affiliation: Division of Pulmonary, Sleep and Critical Care Medicine, Department of Internal Medicine, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Korea.
authors.forename: Seung Heon
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Sung Yong
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Division of Respiratory and Critical Care Medicine, Department of Internal Medicine, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Sang Yeub
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Division of Pulmonary, Sleep and Critical Care Medicine, Department of Internal Medicine, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Korea.
authors.forename: Je Hyeong
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Division of Pulmonary, Sleep and Critical Care Medicine, Department of Internal Medicine, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Korea.
authors.forename: Chol
authors.initials: C
authors.lastname: Shin
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Jae Jeong
authors.initials: JJ
authors.lastname: Shim
authors.affiliation: Division of Respiratory and Critical Care Medicine, Department of Internal Medicine, Korea University Anam Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Kwang Ho
authors.initials: KH
authors.lastname: In
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea.
authors.forename: Kyung Ho
authors.initials: KH
authors.lastname: Kang
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea. Electronic address: minkyunghoon@korea.ac.kr.
authors.forename: Kyung Hoon
authors.initials: KH
authors.lastname: Min
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D002116:Calcitonin / Q000097:blood*; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000175:diagnosis* / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000175:diagnosis* / Q000382:microbiology; D011446:Prospective Studies; D056910:Republic of Korea
chemical_list: D015415:Biomarkers; D002116:Calcitonin
keywords: Bacterial; Interstitial; Lung diseases; Pneumonia; Procalcitonin