title: Which sample tube should be used for routine glucose determination?
abstract: BACKGROUND
  Glucose is one of the most frequently requested analytes in clinical laboratory. Blood glucose analysis is affected from in vitro glycolysis. In order to determine the most suitable blood collection tube for this purpose we have compared different tubes: sodium fluoride, lithium heparin, sodium fluoride/citrate buffer containing tubes and serum with clot activator tube for the measurement of glucose when the tube has been kept at room temperature (RT) for up to 4h.
  
  
  METHODS
  Venous blood was collected from 49 healthy volunteers into Sarstedt S-Monovettes for glucose analysis. Reference plasma glucose was determined in a lithium heparin tube and immediately placed in an ice/water slurry. Within 10min it was centrifuged at 4°C and plasma was separated from the blood cells. Samples have been preserved at RT for 1, 2 and 4h after drawing. Glucose has been determined using a hexokinase method.
  
  
  RESULTS
  Glucose levels tested in a serum with clot activator tube, in lithium heparin and in sodium fluoride/sodium EDTA tubes when compared with lithium-heparin reference plasma did not meet the desirable bias for glucose (±1.8%) when kept at RT for up to 4h. GlucoEXACT tubes, when corrected by the Sarsted recommended factor of 1.16, showed a mean (95% CI) bias of +0.96% (0.45-1.47) at 1h, +1.40% (0.88-1.93) at 2h and +0.95% (0.44-1.46) at 4h, reaching the analytical goal for the desirable bias.
  
  
  CONCLUSIONS
  Samples collected into GlucoEXACT tubes containing sodium fluoride/citrate buffer liquid mixture are equivalent to those collected in reference plasma tubes avoiding glycolysis completely and within a 4h delay in plasma separation.
authors.affiliation: Clinical Chemistry Laboratory, A.O. Spedali Civili, Brescia, Italy. Electronic address: graziella.bonetti@spedalicivili.brescia.it.
authors.forename: Graziella
authors.initials: G
authors.lastname: Bonetti
authors.affiliation: Clinical Chemistry Laboratory, A.O. Spedali Civili, Brescia, Italy.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Cancelli
authors.affiliation: Clinical Chemistry Laboratory, A.O. Spedali Civili, Brescia, Italy.
authors.forename: Giulio
authors.initials: G
authors.lastname: Coccoli
authors.affiliation: Clinical Chemistry Laboratory, A.O. Spedali Civili, Brescia, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Piccinelli
authors.affiliation: Clinical Chemistry Laboratory, A.O. Spedali Civili, Brescia, Italy.
authors.forename: Duilio
authors.initials: D
authors.lastname: Brugnoni
authors.affiliation: Clinical Chemistry Laboratory, A.O. Spedali Civili, Brescia, Italy; Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Caimi
authors.affiliation: Clinical Chemistry and Haematology Laboratory, San Bortolo Hospital, Vicenza, Italy.
authors.forename: Mariarosa
authors.initials: M
authors.lastname: Carta
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D001774:Blood Chemical Analysis / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D001786:Blood Glucose / Q000032:analysis*; D002021:Buffers; D019343:Citric Acid / Q000737:chemistry; D004867:Equipment Design; D005260:Female; D006019:Glycolysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012015:Reference Standards; D015203:Reproducibility of Results; D012969:Sodium Fluoride / Q000737:chemistry; D013048:Specimen Handling / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D013696:Temperature; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D002021:Buffers; D019343:Citric Acid; D012969:Sodium Fluoride
keywords: Citrate acidification; Glucose; Glycolysis inhibition; Hexokinase; Preanalytical conditions; Sodium fluoride; Stability