Maintaining glucose integrity ex-vivo: Impact of preanalytical specimen handling

Abstract

Background
 Adopting the WHO protocol for glucose analysis is arguably impractical in the routine clinical setting. Deviations may develop due to a lack of understanding regarding the impact of glycolysis on the accuracy of results. 
 
 Aim
 We sought to assess the stability of glucose in two different blood collection tubes (BCT), BD Vacutainer® FX ‘Fl-Ox’ and Greiner Vacuette® FC-Mix ‘FC-Mix’ stored at room temperature (RT:18-220C) and 40C over 8.5 days. 
 
 Method
 Each participant provided venous whole blood collected into 51 BCTs; ‘Fl-Ox’ (n=26) and ‘FC-Mix’ (n=25). One FL-Ox sample from each participant was handled according to the WHO recommended method. The remaining BCTs were stored at 4°C/RT prior to analyses at designated study timepoints. Glucose was measured using the hexokinase assay on the Cobas® 8000 platform.
 
 Results
 Participants (n=8,Male=2) were aged 24-56 years. Plasma glucose measured in FI-Ox BCTs according to the WHO sample-handling method had a median concentration of 5.73 mmol/L (Range: 5.39–10.37 mmol/L). Glucose decreased by greater than Minimal Difference (>0.26 mmol/L) in blood collected into Fl-Ox and stored @4°C/RT within 24h of phlebotomy. FC-Mix BCT maintained glucose <0.26mmol/L @4°C over a period of 8.5 days and up to 4 days @RT when compared to the WHO recommended method.
 
 Conclusion 
 Glucose in FC-Mix BCT stored @4°C demonstrated the best agreement with results determined using the WHO specifications. When FC-Mix tubes were stored @RT glucose was stable for 4 days. These findings suggest that the FC-Mix BCT effectively inhibits glycolysis and should be introduced into routine clinical practice.