Stability of glucose in plasma with different anticoagulants

Background: People with hyperglycemia, especially those who are pregnant, depend on accurate blood glucose measurements for correct diagnosis of diabetes and monitoring. Glycolysis after blood draw, however, decreases glucose concentrations in blood that is collected at room temperature in the absence of a stabilizer. Cold temperatures (4 degrees C) inhibit glycolysis; but prompt cooling and processing of each blood sample in the cold is difficult to achieve in routine clinical practice. Therefore, preservatives are used to stabilize glucose during blood collection and processing procedures that are performed at room temperature. This study examined the effect of different anticoagulants (EDTA, heparin, oxalate), with or without glycolysis inhibitors (NaF, citrate), on the stability of glucose in plasma samples - obtained from blood that was collected and stored at room temperature for up to 24 h. Methods: Venous blood was collected from 60 volunteers; each donor blood sample was divided into six tubes, each one containing a different anti-glycolysis-anticoagulant composition. Terumo VENOSAFE (TM) Glycemia tubes contained NaF/citrate buffer)/Na(2)EDTA; NaF/Na-heparin; and NaF/K(2)oxalate. Sarstedt tubes contained NaF/citrate; NaF/Na(2)EDTA; and K(2)EDTA. At 0, 2, 8 and 24 h, plasma was obtained for glucose measurements using the Glucose Hexokinase and Glucose Oxidase methods, and the ADVIA (R) 1800 Clinical Chemistry System. Results: Both methods demonstrated minimal glycolysis by 24 h (<3.8%) for the three Terumo VENOSAFE (TM) Glycemia tubes, and the Sarstedt S-Monovette GlucoEXACT tube that contained NaF/citrate. Glycolysis was higher in tubes containing NaF/Na(2)EDTA-alone (11.7%) and K(2)EDTA-alone (85%). Conclusions: Terumo VENOSAFE (TM) Glycemia tubes (containing NaF/citrate buffer/Na(2)EDTA; NaF/Na-heparin; and NaF/K(2)oxalate) and the Sarstedt S-Monovette (R) GlucoEXACT tubes (containing NaF/citrate) are suitable for shipping venous whole blood samples to the testing laboratory within 24 h at room temperature.