Background: Clinical laboratories often face practical concerns regarding the shipment condition of clinical specimens when considering the accuracy of glucose concentration test results. Therefore, the aims of this study were to explore whether the choice of the sample collection method has any effect on subsequent glucose measurements and to compare glucose stability in different shipment conditions at room temperature for up to 10 hours.
Methods: Paired fasting venous blood samples from 58 volunteers were collected in NaF/citrate tubes and in serum tubes without any additive. At 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 hours, glucose levels were measured on a Hitachi 7600-020 analyzer using the Glucose GOD-PAP method.
Results: The mean measured glucose concentration was significantly higher in plasma than in serum (5.07 ? 0.33 mmol/L vs. 4.79 ? 0.38 mmol/L, respectively, p < 0.001) at 0 hours. Passing-Bablok regression revealed a significant difference between the plasma and serum samples. The regression equation was y = 0.765 + 0.893 x (intercept A 95% CI: 0.405 -1.158; slope B 95% CI: 0.812-0.968). A negative bias of 0.28 mmol/L (95% CI: 0.00-0.56) was observed for samples collected in serum tubes. Similar results were found at the other ten time points (1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 hours). Glycolysis was higher in serum tubes (13.4%) than in NaF/citrate tubes (2%) after 10 hours at room temperature.
Conclusions: Compared to the serum tube, NaF/citrate plasma tube is suitable for shipping venous whole blood samples within 10 hours at room temperature without undergoing significant glycolysis.