title: Cardiac troponin I levels and alveolar-arterial oxygen gradient in patients with community-acquired pneumonia.
abstract: BACKGROUND
  Patients with community-acquired pneumonia (CAP) appear to have cardiac stress as demonstrated by elevated B-type natriuretic peptide (BNP). We hypothesised that myocardial stress and decrease in oxygenation might also lead to elevations of cardiac troponin I (cTnI) levels in serum.
  
  
  OBJECTIVE
  The aim of this study was to see if cTnI was associated with the alveolar-arterial oxygen gradient (DeltaA-a), a marker of severity in CAP.
  
  
  METHODS
  Retrospective cohort study of 901 CAP patients with no evidence of acute coronary syndrome presenting to a large, tertiary-care, urban teaching hospital over a 3-year period.
  
  
  RESULTS
  A strong linear trend between log(10)cTnI and DeltaA-a was observed (r(2)=0.76) with a statistically significant Spearman correlation coefficient (r(s)=0.75; p<0.0001) between cTnI and DeltaA-a. A cTnI value of 0.5 ng/ml discriminated mild CAP from moderate-severe CAP with an OR=208 (95% CI: 50.5-408; p<0.0001).
  
  
  CONCLUSIONS
  These data suggest that decreased blood O(2) levels as suggested by elevated DeltaA-a may lead to acute myocardial damage and that cTnI may be useful as a biomarker to stratify risk in subjects with CAP.
authors.affiliation: Division of Pulmonary Medicine, Department of Internal Medicine, St Joseph's Regional Medical Center, Paterson, NJ, United States.
authors.forename: Mahmoud Q
authors.initials: MQ
authors.lastname: Moammar
authors.forename: Muhammad I
authors.initials: MI
authors.lastname: Ali
authors.forename: Nader A
authors.initials: NA
authors.lastname: Mahmood
authors.forename: Vincent A
authors.initials: VA
authors.lastname: DeBari
authors.forename: M Anees
authors.initials: MA
authors.lastname: Khan
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D017714:Community-Acquired Infections / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000097:blood / Q000378:metabolism*; D018410:Pneumonia, Bacterial / Q000097:blood*; D011650:Pulmonary Alveoli / Q000098:blood supply* / Q000378:metabolism; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013312:Stress, Physiological; D019210:Troponin I / Q000097:blood*
chemical_list: D015415:Biomarkers; D019210:Troponin I; D010100:Oxygen