Effective inhibition of glycolysis in venous whole blood and plasma samples1)

Abstract

Abstract Background: To stabilize glucose immediately and to prevent preanalytical loss of glucose from blood samples after collection, additional acidification is needed. Methods: In this study, we aimed to assess the value of citrate-buffered GlucoEXACT tubes (Sarstedt) compared to VenoSafe™ Glycaemia (Terumo) tubes. Conventional sodium fluoride (NaF) tubes were used as internal controls. First, stability of venous plasma glucose concentrations were compared in 10 healthy volunteers at nine definite time points (after 0, 0.5, 1, 1.5, 2, 3, 4, 8, and 12 h). Blood samples from VenoSafe™ Glycaemia and NaF tubes were immediately centrifuged and separated. Moreover, glucose concentrations in an additional five healthy volunteers were compared by collecting blood samples simultaneously in GlucoEXACT and VenoSafe™ Glycaemia tubes and storing for 0, 1, 2, 4, 12, 24, and 48 h until centrifugation. Dilution- and hematocrit-dependent bias of plasma glucose in GlucoEXACT tubes was assessed by serial dilution. Results: Mean Terumo plasma glucose concentrations decreased within the first 4 h from 94.9 mg/dL to 92.5 mg/dL (–2.5%) and remained stable after 12 h. Mean conventional NaF plasma glucose concentrations decreased within the first 4 h from 90 mg/dL to 87 mg/dL (–3.3%, not significant) and decreased significantly after 12 h (82.6 mg/dL, –8.2%). There was no significant decrease or difference of plasma glucose levels in stored blood samples collected in GlucoEXACT and VenoSafe™ Glycaemia tubes [linear regression analysis: R2=0.9688; GlucoEXACT (y)=5.3871+0.9431× VenoSafe™ Glycaemia (x); Wilcoxon test, p=0.7125]. Citrate buffer in GlucoEXACT tubes does not impair glucose concentration. Conclusions: Determination of plasma glucose concentration in GlucoEXACT tubes is a suitable diagnostic alternative compared with Terumo VenoSafe™ Glycaemia tubes.