title: Acidification of blood is superior to sodium fluoride alone as an inhibitor of glycolysis.
abstract: BACKGROUND
  Sodium fluoride is the preferred agent to inhibit glycolysis. Its action is not immediate, however, and complete inhibition is delayed for up to 4 hours. A more effective method is needed. Acidification of blood combined with the addition of NaF and EDTA appears to be such a method. We studied whether acidification was indeed more effective than NaF.
  
  
  METHODS
  We conducted 6 independent studies over a 10-month period at 3 Quest Diagnostics laboratory sites. In each study, we drew venous blood from 6-24 nonfasting employee volunteers into 3 or 4 different serum- or plasma-collection tubes, which were stored under different conditions and aliquoted at different times. We analyzed the aliquots in duplicate by means of a hexokinase-based enzymatic method.
  
  
  RESULTS
  The mean glucose concentration decreased by 0.3% at 2 h and by 1.2% at 24 h when blood was drawn into tubes containing citrate buffer, NaF, and EDTA. In contrast, the mean glucose concentration decreased by 4.6% at 2 h and by 7.0% at 24 h when blood was drawn into tubes containing NaF and sodium oxalate.
  
  
  CONCLUSIONS
  Acidification should replace NaF alone as the recommended method for obtaining an accurate glucose concentration. Diagnostic cut points based on blood samples collected into tubes containing NaF as the only inhibitor of glycolysis are likely to be too low.
authors.affiliation: Quest Diagnostics, Deerfield Beach, FL 33442-7727, USA. Raymond.X.Gambino@questdiagnostics.com
authors.forename: Raymond
authors.initials: R
authors.lastname: Gambino
authors.forename: Janet
authors.initials: J
authors.lastname: Piscitelli
authors.forename: Tomy A
authors.initials: TA
authors.lastname: Ackattupathil
authors.forename: Judy L
authors.initials: JL
authors.lastname: Theriault
authors.forename: Reynaldo D
authors.initials: RD
authors.lastname: Andrin
authors.forename: Michael L
authors.initials: ML
authors.lastname: Sanfilippo
authors.forename: Monina
authors.initials: M
authors.lastname: Etienne
mesh_terms: D001769:Blood / Q000187:drug effects*; D001786:Blood Glucose / Q000737:chemistry*; D001793:Blood Preservation / Q000379:methods*; D002951:Citrates / Q000737:chemistry*; D003920:Diabetes Mellitus / Q000097:blood*; D006019:Glycolysis / Q000187:drug effects*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D012969:Sodium Fluoride / Q000737:chemistry*; D013048:Specimen Handling / Q000379:methods
chemical_list: D001786:Blood Glucose; D002951:Citrates; D012969:Sodium Fluoride