title: Non-commutability of results of highly sensitive troponin I and T immunoassays.
abstract: BACKGROUND
  The measurement of cardiospecific troponins is pivotal in the diagnostic and prognostic approach of patients with suspected acute myocardial infarction (AMI). However, no information is available on the commutability of results between the novel highly-sensitive (HS) troponin T (TnT) and I (TnI) immunoassays.
  
  
  METHODS
  The study population consisted in 47 consecutive patients presenting at the emergency department (ED) of the Academic Hospital of Parma with suspected AMI. TnI was measured with the novel prototype Beckman Coulter HS-AccuTnI immunoassay on Access 2, whereas TnT was measured with the Roche HS-TnT immunoassay on Cobas.
  
  
  RESULTS
  Eight out of the 47 patients (17%) were finally diagnosed as having an AMI. The overall correlation between TnT and TnI for total patient group was acceptable (r = 0.944; P < 0.01). Nevertheless, when the analysis of data was carried out in separate groups according to the final diagnosis of AMI, two different equation results were obtained, i.e., HS-TnT = HS-AccuTnI x 0.349 + 20 (r = 0.823; P < 0.01) in non-AMI patients, and HS-TnT = HS-AccuTnI x 0.134 + 67 (r = 0.972; P < 0.01) in those with AMI.
  
  
  CONCLUSIONS
  This study suggests the existence of two biological relationships between Tnl and TnT in plasma, depending on the source of release from the myocardium. Moreover, the non-commutability of data between HS-TnT and HS-AccuTnI jeopardizes the clinical decision making, makes it impossible to calculate the delta or reference change value using the two biomarkers and to finally establish a reliable kinetics of troponin release from the injured myocardium.
authors.affiliation: U.O. di Diagnostica Ematochimica, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy. glippi@ao.pr.it
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lippi
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Cervellin
authors.forename: Rosalia
authors.initials: R
authors.lastname: Aloe
authors.forename: Martina
authors.initials: M
authors.lastname: Montagnana
authors.forename: Gian Luca
authors.initials: GL
authors.lastname: Salvagno
authors.forename: Gian Cesare
authors.initials: GC
authors.lastname: Guidi
mesh_terms: D015415:Biomarkers / Q000097:blood*; D006801:Humans; D007118:Immunoassay; D009203:Myocardial Infarction / Q000097:blood* / Q000175:diagnosis*; D011379:Prognosis; D012015:Reference Standards; D015203:Reproducibility of Results; D019210:Troponin I / Q000097:blood*; D020107:Troponin T / Q000097:blood*
chemical_list: D015415:Biomarkers; D019210:Troponin I; D020107:Troponin T