title: Troponin T percentiles from a random population sample, emergency room patients and patients with myocardial infarction.
abstract: BACKGROUND
  High-sensitivity cardiac troponin T (cTnT) assays detect small clinically important myocardial infarctions (MI) but also yield higher rates of false-positive results owing to increased concentrations sometimes present in patients without MI. Better understanding is needed of factors influencing the 99th percentile of cTnT concentrations across populations and the frequency of changes in cTnT concentrations >20% often used in combination with increased cTnT concentrations for diagnosis of MI.
  
  
  METHODS
  cTnT percentiles were determined by use of the Elecsys® hscTnT immunoassay (Modular® Analytics E170) in a random population sample, in emergency room (ER) patients, and in patients with non-ST-elevation MI (NSTEMI). Changes in cTnT concentrations were determined in hospitalized patients without MI.
  
  
  RESULTS
  The 99th cTnT percentile in a random population sample (median age, 65 years) was 24 ng/L. In ER patients <65 years old without obvious conditions that increase cTnT, the 99th cTnT percentile was 12 ng/L with little age dependence, whereas in those >65 years old it was 82 ng/L and highly age dependent. In hospitalized patients without MI the 97.5th percentile for change in the cTnT concentration was 51%-67%. cTnT remained below the 99th percentile (12 ng/L) in 1% of patients with NSTEMI until 8.5 h after symptom onset and 6 h after ER arrival.
  
  
  CONCLUSIONS
  Age >65 years was the dominant factor associated with increased cTnT in ER patients. This age association was more prominent in ER patients than in a random population sample. Changes in serial cTnT concentrations >20% were common in hospitalized patients without MI.
authors.affiliation: Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. ola.hammarsten@clinchem.gu.se
authors.forename: Ola
authors.initials: O
authors.lastname: Hammarsten
authors.forename: Michael L X
authors.initials: ML
authors.lastname: Fu
authors.forename: Runa
authors.initials: R
authors.lastname: Sigurjonsdottir
authors.forename: Max
authors.initials: M
authors.lastname: Petzold
authors.forename: Lina
authors.initials: L
authors.lastname: Said
authors.forename: Kerstin
authors.initials: K
authors.lastname: Landin-Wilhelmsen
authors.forename: Bengt
authors.initials: B
authors.lastname: Widgren
authors.forename: Mårten
authors.initials: M
authors.lastname: Larsson
authors.forename: Per
authors.initials: P
authors.lastname: Johanson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D007118:Immunoassay; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood* / Q000175:diagnosis; D010361:Patients; D012680:Sensitivity and Specificity; D020107:Troponin T / Q000097:blood*
chemical_list: D020107:Troponin T