title: Specimen recentrifugation and elevated troponin I levels.
abstract: OBJECTIVE
  To compare troponin I levels in plasma before and after specimen recentrifugation.
  
  
  METHODS
  Over a period of 24 consecutive days, we recentrifuged 189 plasma specimens in which the troponin I level was higher than the positivity cut off (60 ng/L) and then remeasured the troponin I.
  
  
  RESULTS
  Two-tailed Wilcoxon matched-pairs test results identified a statistically significant difference between troponin I concentrations before and after recentrifugation (P <.01). For 94 specimens close to the cut-off value (below the 50th percentile among the overall sample of 189 specimens), Passing-Bablok regression analysis showed a median reduction of 10 ng/L (95% confidence interval, -37.5 ng/L - -10.0 ng/L) in the concentrations of troponin I after recentrifugation.
  
  
  CONCLUSIONS
  Specimen recentrifugation is followed by a reduction in troponin I concentrations in specimens with elevated cardiac troponin I, posing a risk for misclassification of patients. Moreover, this practice gives rise to unnecessary prolongation of turnaround time.
authors.affiliation: Department of Laboratory Medicine, Clinical Analysis Laboratory, University Hospital of Modena, and simone.canovi@studio.unibo.it.
authors.forename: Simone
authors.initials: S
authors.lastname: Canovi
authors.affiliation: Department of Laboratory Medicine, Clinical Analysis Laboratory, University Hospital of Modena, and.
authors.forename: Daniele
authors.initials: D
authors.lastname: Campioli
authors.affiliation: Department of Diagnostic, Clinical and Public Health Medicine, University of Modena and Reggio Emilia.
authors.forename: Luigi
authors.initials: L
authors.lastname: Marcheselli
mesh_terms: D001800:Blood Specimen Collection; D002498:Centrifugation; D005260:Female; D006801:Humans; D008297:Male; D012044:Regression Analysis; D013997:Time Factors; D019210:Troponin I / Q000032:analysis / Q000097:blood*
chemical_list: D019210:Troponin I
keywords: cardiac biomarkers; cardiovascular disease; clinical chemistry; preanalysis; recentrifugation; troponin I