title: Longitudinal studies of cardiac troponin I in a large cohort of healthy children.
abstract: BACKGROUND
  There is little information available on cardiac troponin concentrations in healthy young children.
  
  
  METHODS
  Using a precommercial high-sensitivity assay from Abbott Diagnostics, we measured cardiac troponin I (cTnI) in longitudinal blood samples collected at ages 8, 10, and 12 years from a cohort of healthy, community-dwelling children. The 99th percentile values were calculated and estimates of the long-term biological variation were made.
  
  
  RESULTS
  cTnI concentrations were above the limit of detection in 87%, 90%, and 98% of the children at ages 8, 10, and 12 years. The 99th percentiles were lower compared to a healthy adult population in both male and female children at all ages studied. At the 3 periods of study assessment, different children had cTnI concentrations above the 99th percentile. The calculated 99th percentile varied markedly depending upon whether the lowest or highest cTnI measurement for an individual child was included in the calculation. Biological variation varied markedly between 0% and 136%, the index of individuality was low at 0.36, and the reference change value was an increase of 147% or a decrease of 59%.
  
  
  CONCLUSIONS
  In this longitudinal study of cTnI concentrations in healthy children as determined by a high-sensitivity assay, different children had concentrations of cTnI above the 99th percentile at the 3 episodes of assessment. These results suggest that in children the 99th percentile may not be a reliable index of silent cardiac disease, but rather may be indicating low-grade intercurrent illness.
authors.affiliation: ACT Pathology, Garran, Australia.
authors.forename: Gus
authors.initials: G
authors.lastname: Koerbin
authors.forename: Julia M
authors.initials: JM
authors.lastname: Potter
authors.forename: Walter P
authors.initials: WP
authors.lastname: Abhayaratna
authors.forename: Richard D
authors.initials: RD
authors.lastname: Telford
authors.forename: Tony
authors.initials: T
authors.lastname: Badrick
authors.forename: Fred S
authors.initials: FS
authors.lastname: Apple
authors.forename: Allan S
authors.initials: AS
authors.lastname: Jaffe
authors.forename: Peter E
authors.initials: PE
authors.lastname: Hickman
mesh_terms: D002648:Child; D005260:Female; D006801:Humans; D057230:Limit of Detection; D008137:Longitudinal Studies; D008297:Male; D012016:Reference Values; D019210:Troponin I / Q000097:blood*
chemical_list: D019210:Troponin I