Blood Collection Tubes Compared for Glucose Values

Blood specimens for plasma glucose analysis have been collected in tubes which contain sodium fluoride (NaF), to prevent coagulation and glycolysis, and an inhibitor potassium oxalate (KOx) and compared with samples collected in barrier serum tubes.

Scientists at the University of Ottawa (ON, Canada) collected serum and plasma samples were under field conditions from a single draw of 3,692 individuals. Collection was performed using a 4.0 mL plasma NaF/KOx tube and a 7.5 mL serum separator tubes (SST) tube; both are from the BD Vacutainer range (Becton–Dickinson; Franklin Lakes, NJ, USA).

Plasma and serum specimens were analyzed on a Vitros 5.1 FS analyzer (Ortho-Clinical Diagnostics Inc. Raritan, NJ, USA) using the VITROS GLUSlide method, which has a multilayered, analytical element coated on a polyester support. Paired specimens from both SST and NaF/KOx draws from each respondent were analyzed using the same lot of reagent, eliminating any lot-to-lot variability in the results.

A total of 495 paired samples were used in the final comparison. There was a high rate of 86.2% hemolysis in the NaF/KOx tubes, while hemolysis was infrequently observed with only 2% the SST tubes. Comparing only blood draws where no hemolysis was observed in both tubes showed no effect of tube type on serum/plasma glucose concentrations. This was also observed when data was restricted to cases when only SST samples were not hemolyzed. The mean glucose concentrations measured in plasma was 4.85 ± 1.25 mmol/L and in serum was 4.84 ± 1.24 mmol/L, which was not significantly different.

The authors concluded that both collection tubes can be used under survey collection and processing conditions to measure glucose with this assay system with no difference in reported results. The elimination of NaF/KOx tubes would provide process and operational advantages and a significant cost saving measure for national population-based surveys. The study was published in the March 2013 issue of the journal Clinical Biochemistry.

Related Links:
University of Ottawa
Becton–Dickinson
Ortho-Clinical Diagnostics Inc.