title: Determination of 19 cardiac troponin I and T assay 99th percentile values from a common presumably healthy population.
abstract: BACKGROUND
  Between-assay comparability of 99th percentiles for cardiac troponin concentrations has not been assessed systematically in a single population for a large number of assays.
  
  
  METHODS
  We determined 99th percentiles for 19 cardiac troponin assays in heparin plasma samples from a population of 272 and 252 presumably healthy males and females, respectively. The assays evaluated included 1 cardiac troponin T (cTnT) assay from Roche and 18 cTnI assays from Abbott, Alere, Beckman, bioMerieux, Instrumentation Laboratory, Ortho-Clinical Diagnostics, Singulex, Siemens, and Roche. Five of these assays were categorized as high-sensitivity, 9 as sensitive-contemporary, and 5 as point-of-care (POC) assays.
  
  
  RESULTS
  For high-sensitivity cTnI (hs-cTnI) assays 99th percentiles varied from 23 to 58 ng/L. At least 80% of individuals had measurable hs-cTnI, whereas only 25% had measurable high-sensitivity cTnT. All high-sensitivity cardic troponin assays had 99th percentiles that were 1.2-2.4-fold higher in males than females. For the 9 sensitive-contemporary cTnI assays, 99th percentiles varied from 12 to 392 ng/L, and only the Beckman assay gave measurable concentrations in a substantial portion of the population (35% vs ≤6% for the others). Seven of these 9 assays had 1.3-5.0-fold higher 99th percentiles for males than females. For 5 cTnI POC assays, 99th percentiles varied from <10 to 40 ng/L. The Instrumentation Laboratory assay gave measurable results in 27.8% of study participants vs ≤6% for the others. Correlations were generally poor among assays.
  
  
  CONCLUSIONS
  Among cardiac troponin assays 99th percentile concentrations appear to differ. High-sensitivity assays provide measurable cardiac troponin results in a substantially greater fraction of presumably healthy individuals.
authors.affiliation: Hennepin County Medical Center Department of Laboratory Medicine and Pathology, Minneapolis, MN 55415, USA. apple004@umn.edu
authors.forename: Fred S
authors.initials: FS
authors.lastname: Apple
authors.forename: Ranka
authors.initials: R
authors.lastname: Ler
authors.forename: MaryAnn M
authors.initials: MM
authors.lastname: Murakami
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007118:Immunoassay; D008297:Male; D008875:Middle Aged; D019095:Point-of-Care Systems; D012016:Reference Values; D012680:Sensitivity and Specificity; D012737:Sex Factors; D019210:Troponin I / Q000097:blood*; D020107:Troponin T / Q000097:blood*; D055815:Young Adult
chemical_list: D019210:Troponin I; D020107:Troponin T