title: Plasma creatinine in dogs: intra- and inter-laboratory variation in 10 European veterinary laboratories.
abstract: BACKGROUND
  There is substantial variation in reported reference intervals for canine plasma creatinine among veterinary laboratories, thereby influencing the clinical assessment of analytical results. The aims of the study was to determine the inter- and intra-laboratory variation in plasma creatinine among 10 veterinary laboratories, and to compare results from each laboratory with the upper limit of its reference interval.
  
  
  METHODS
  Samples were collected from 10 healthy dogs, 10 dogs with expected intermediate plasma creatinine concentrations, and 10 dogs with azotemia. Overlap was observed for the first two groups. The 30 samples were divided into 3 batches and shipped in random order by postal delivery for plasma creatinine determination. Statistical testing was performed in accordance with ISO standard methodology.
  
  
  RESULTS
  Inter- and intra-laboratory variation was clinically acceptable as plasma creatinine values for most samples were usually of the same magnitude. A few extreme outliers caused three laboratories to fail statistical testing for consistency. Laboratory sample means above or below the overall sample mean, did not unequivocally reflect high or low reference intervals in that laboratory.
  
  
  CONCLUSIONS
  In spite of close analytical results, further standardization among laboratories is warranted. The discrepant reference intervals seem to largely reflect different populations used in establishing the reference intervals, rather than analytical variation due to different laboratory methods.
authors.affiliation: Ål and Hol Veterinary Clinic, 3570 Ål, Norway.
authors.forename: Tina
authors.initials: T
authors.lastname: Ulleberg
authors.forename: Joris
authors.initials: J
authors.lastname: Robben
authors.forename: Kathrine M
authors.initials: KM
authors.lastname: Nordahl
authors.forename: Thomas
authors.initials: T
authors.lastname: Ulleberg
authors.forename: Reidun
authors.initials: R
authors.lastname: Heiene
mesh_terms: D000818:Animals; D003404:Creatinine / Q000097:blood*; D004285:Dogs / Q000097:blood*; D005060:Europe; D011897:Random Allocation; D012016:Reference Values; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires
chemical_list: D003404:Creatinine