title: Evaluation of the in vitro interference of bilirubin and lipids in the measurement of the plasma glutathione reductase activity.
abstract: BACKGROUND
  The pre-analytical phase is the most vulnerable to errors, and some of the most common interferents in laboratory routine are bilirubin and lipemia. Therefore, the aim of this study was to evaluate the in vitro interference of bilirubin and lipids in the measurement of the activity of glutathione reductase (GR) in plasma samples.
  
  
  METHODS
  The evaluation of the in vitro interference of bilirubin was performed by addition of bilirubin to a plasma pool at the following final concentrations: 0.9, 1.9, 3.8, 7.5, 15, and 30 mg/dL. The turbidity of lipemia was simulated by the addition of Intralipid to the plasma pool at the following final concentrations: 0.67, 1.25, 2.5, 5, and 10 mg/dL. GR activity was measured on a Cobas MIRA automated analyzer.
  
  
  RESULTS
  Plasma GR activity was significantly affected by bilirubin and lipids. At the concentrations of 0.9 to 30 mg/dL of bilirubin added, the decrease of GR activity ranged between 22.9 to 45.4%. At the concentrations of 0.67 to 10 mg/dL of Intralipid added, the decrease of GR activity ranged between 22.4 to 36.5%.
  
  
  CONCLUSIONS
  The addition of bilirubin and lipids in plasma samples interferes negatively in the measurement of GR activity, since GR values are reduced in the presence of these in vitro interferents.
authors.forename: Carine L
authors.initials: CL
authors.lastname: Hermes
authors.forename: Taís C
authors.initials: TC
authors.lastname: Almeida
authors.forename: Bruna S
authors.initials: BS
authors.lastname: Hausen
authors.forename: Lara P
authors.initials: LP
authors.lastname: Cargnin
authors.forename: Etiane
authors.initials: E
authors.lastname: Tatsch
authors.forename: José A M
authors.initials: JA
authors.lastname: De Carvalho
authors.forename: Rafael N
authors.initials: RN
authors.lastname: Moresco
mesh_terms: D001331:Automation; D001663:Bilirubin / Q000097:blood* / Q000737:chemistry; D019411:Clinical Laboratory Techniques; D004305:Dose-Response Relationship, Drug; D005980:Glutathione Reductase / Q000097:blood*; D006801:Humans; D006949:Hyperlipidemias / Q000097:blood; D008055:Lipids / Q000097:blood* / Q000737:chemistry; D009391:Nephelometry and Turbidimetry; D015203:Reproducibility of Results
chemical_list: D008055:Lipids; D005980:Glutathione Reductase; D001663:Bilirubin