Rapid blood separation is superior to fluoride for preventing in vitro reductions in measured blood glucose concentration.
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.
Shi
R Z
RZ
Department of Pathology, Stanford University, Stanford, California, USA. rzshi@stanford.edu
Seeley
E S
ES
Bowen
R
R
Faix
J D
JD
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
D001786:Blood Glucose; D012969:Sodium Fluoride; D006493:Heparin; D008094:Lithium