title: Clinical significance of initial troponin I in the grey zone in emergency department chest pain patients: a retrospective pilot study.
abstract: OBJECTIVE
  'Normal' range for cardiac troponin I (TnI) has changed with more sensitive tests, but the validity of low-level elevations is contentious. We aimed to describe the characteristics and outcome of patients with an initial TnI level 1-5 times the upper limit of normal.
  
  
  METHODS
  Retrospective study of patients assessed for ACS with initial TnI level between 0.05-0.19 ng/ml. Data collected included demographics, clinical data, TnI levels and outcome. Primary outcome was the proportion of patients who had a serial TnI rise consistent with ACS.
  
  
  RESULTS
  72 patients were studied; median age 71, median TIMI score 3, 66.7% male. 35 patients (48.6%) had a TnI rise consistent with ACS.
  
  
  CONCLUSIONS
  Approximately half of patients with initial TnI between 0.05-0.19 ng/ml had a TnI rise consistent with ACS. An initial TnI in this range is not, of itself, indicative of ACS. Clinical decision-making should be guided by clinical features and serial TnI measurement.
authors.affiliation: Department of Emergency Medicine, Western Health, Footscray, Australia.
authors.forename: Hwee Min
authors.initials: HM
authors.lastname: Lee
authors.forename: Debra
authors.initials: D
authors.lastname: Kerr
authors.forename: Darach
authors.initials: D
authors.lastname: O'H Ici
authors.forename: Anne-Maree
authors.initials: AM
authors.lastname: Kelly
mesh_terms: D054058:Acute Coronary Syndrome / Q000097:blood / Q000175:diagnosis*; D000368:Aged; D000369:Aged, 80 and over; D000553:Ambulatory Care / Q000379:methods; D015415:Biomarkers / Q000097:blood; D002637:Chest Pain / Q000097:blood*; D015331:Cohort Studies; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D012189:Retrospective Studies; D016896:Treatment Outcome; D019210:Troponin I / Q000097:blood*
chemical_list: D015415:Biomarkers; D019210:Troponin I