title: Rapid blood separation is superior to fluoride for preventing in vitro reductions in measured blood glucose concentration.
abstract: OBJECTIVE
  To determine whether tubes containing sodium fluoride negatively bias blood glucose concentration by directly comparing glucose concentrations in paired blood samples collected in tubes containing lithium heparin (Li-Heparin) and tubes containing sodium fluoride/potassium oxalate (NaF-KOx).
  
  
  METHODS
  Paired blood samples from a group of patients (n = 1040) were collected in tubes containing Li-Heparin and tubes containing NaF-KOx at the same time. All Li-Heparin samples were centrifuged soon after collection and were kept cool in transport along with NaF-KOx samples, which were centrifuged at the receiving location after an average transport time of 4 h, but immediately before analysis. Glucose concentrations in the paired samples were determined simultaneously by an automated oxidase method.
  
  
  RESULTS
  The mean glucose concentrations for NaF-KOx samples and Li-Heparin samples were 5.7 mmol/l and 6.1 mmol/l, respectively, with a mean difference of 0.39 mmol/l.
  
  
  CONCLUSIONS
  Rapid separation of heparinised blood is superior to fluoride alone for abrogating glycolytic effects on blood glucose measurements in the clinical laboratory.
authors.affiliation: Department of Pathology, Stanford University, Stanford, California, USA. rzshi@stanford.edu
authors.forename: R Z
authors.initials: RZ
authors.lastname: Shi
authors.forename: E S
authors.initials: ES
authors.lastname: Seeley
authors.forename: R
authors.initials: R
authors.lastname: Bowen
authors.forename: J D
authors.initials: JD
authors.lastname: Faix
mesh_terms: D001786:Blood Glucose / Q000032:analysis* / Q000187:drug effects; D001800:Blood Specimen Collection / Q000379:methods*; D002498:Centrifugation; D006019:Glycolysis / Q000187:drug effects; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D008094:Lithium / Q000494:pharmacology; D015203:Reproducibility of Results; D012969:Sodium Fluoride / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D012969:Sodium Fluoride; D006493:Heparin; D008094:Lithium