title: The Roche Immunoturbidimetric Albumin Method on Cobas c 501 Gives Higher Values Than the Abbott and Roche BCP Methods When Analyzing Patient Plasma Samples.
abstract: BACKGROUND
  Serum/plasma albumin is an important and widely used laboratory marker and it is important that we measure albumin correctly without bias. We had indications that the immunoturbidimetric method on Cobas c 501 and the bromocresol purple (BCP) method on Architect 16000 differed, so we decided to study these methods more closely.
  
  
  METHODS
  A total of 1,951 patient requests with albumin measured with both the Architect BCP and Cobas immunoturbidimetric methods were extracted from the laboratory system. A comparison with fresh plasma samples was also performed that included immunoturbidimetric and BCP methods on Cobas c 501 and analysis of the international protein calibrator ERM-DA470k/IFCC.
  
  
  RESULTS
  The median difference between the Abbott BCP and Roche immunoturbidimetric methods was 3.3 g/l and the Roche method overestimated ERM-DA470k/IFCC by 2.2 g/l. The Roche immunoturbidimetric method gave higher values than the Roche BCP method: y = 1.111x - 0.739, R² = 0.971.
  
  
  CONCLUSIONS
  The Roche immunoturbidimetric albumin method gives clearly higher values than the Abbott and Roche BCP methods when analyzing fresh patient samples. The differences between the two methods were similar at normal and low albumin levels.
authors.affiliation: Department of Medical Sciences, Clinical Chemistry, University Hospital, Uppsala, Sweden.
authors.forename: Johanna
authors.initials: J
authors.lastname: Helmersson-Karlqvist
authors.affiliation: Department of Medical Sciences, Clinical Chemistry, University Hospital, Uppsala, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Flodin
authors.affiliation: Department of Clinical Chemistry, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Aleksandra Mandic
authors.initials: AM
authors.lastname: Havelka
authors.affiliation: Department of Medical Sciences, Clinical Chemistry, University Hospital, Uppsala, Sweden.
authors.forename: Xiao Yan
authors.initials: XY
authors.lastname: Xu
authors.affiliation: Department of Medical Sciences, Clinical Chemistry, University Hospital, Uppsala, Sweden. anders.larsson@akademiska.se.
authors.forename: Anders
authors.initials: A
authors.lastname: Larsson
mesh_terms: D001962:Bromcresol Purple / Q000737:chemistry*; D002138:Calibration; D006801:Humans; D009391:Nephelometry and Turbidimetry / Q000295:instrumentation* / Q000379:methods*; D010949:Plasma / Q000737:chemistry*; D012709:Serum Albumin / Q000032:analysis*
chemical_list: D012709:Serum Albumin; D001962:Bromcresol Purple
keywords: BCP; albumin; bromocresol purple; calibration; immunoturbidimetric method; turbidimetry