Time and temperature affect glycolysis in blood samples regardless of fluoride-based preservatives: a potential underestimation of diabetes

Abstract

Background The inhibition of glycolysis prior to glucose measurement is an important consideration when interpreting glucose tolerance tests. This is particularly important in gestational diabetes mellitus where prompt diagnosis and treatment is essential. A study was planned to investigate the effect of preservatives and temperature on glycolysis. Methods Blood samples for glucose were obtained from consented females. Lithium heparin and fluoride-EDTA samples transported rapidly in ice slurry to the laboratory were analysed for glucose concentration and then held either in ice slurry or at room temperature for varying time intervals. Paired fluoride-citrate samples were received at room temperature and held at room temperature, with analysis at similar time intervals. Results No significant difference was noted between mean glucose concentrations when comparing different sample types received in ice slurry. The mean glucose concentrations decreased significantly for both sets of samples when held at room temperature (0.4 mmol/L) and in ice slurry (0.2 mmol/L). A review of patient glucose tolerance tests reported in our hospital indicated that 17.8% exceeded the recommended diagnostic criteria for gestational diabetes mellitus. It was predicted that if the results of fasting samples were revised to reflect the effect of glycolysis at room temperature, the adjusted diagnostic rate could increase to 35.3%. Conclusion Preanalytical handling of blood samples for glucose analysis is vital. Fluoride-EDTA is an imperfect antiglycolytic, even when the samples are transported and analysed rapidly provides such optimal conditions. The use of fluoride-citrate tubes may offer a viable alternative in the diagnosis of diabetes mellitus.

Utility Assessment of Glyceraldehyde additive for the preservation of blood glucose and its interferences with other clinical chemistry parameters

“…To overcome this problem, it is recommended that sodium fluoride preserved blood samples should be analyzed within 30 minutes of collection, if the delay is suspected, then plasma should be separated within 30 minutes to get reliable results (Greene et al, 2010). A decrease in glucose levels during the first three hours has also been advocated by del Pino et al, who compared the glucose levels in sodium fluoride tubes at different intervals and found significant differences till 180 minutes after collection (Stapleton et al, 2017). However, Sodium fluoride is still a commonly used tube for glucose analysis and the results of the glyceraldehyde tube are comparable with sodium fluoride tube with the advantage of less or no interferences with other chemistry parameters like urea, sodium, and potassium in the samples preserved in glyceraldehyde (Pasqualetti et al, 2017).…”

“…Glycolysis occurs in blood samples and glucose level decreases by 5-7% that is 10 mg/dl (0.6 mmol/dl) in one hour (Greene et al, 2010). Therefore either glycolytic inhibitor should be used as glucose preservatives or it should separate from cells within 30 minutes of collection (Stapleton et al, 2017). Different preservatives are used to prevent glycolysis and to maintain glucose levels in blood samples, but sodium fluoride is one of the most commonly used glucose preservatives (Pasqualetti et al, 2017).…”

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

“…These authors estimated that if the fasting glucose result was amended to reflect the quantity of glucose loss due to glycolysis when the WHO recommended approach is not followed, the diagnosis of GDM in their population would more than double. 27 It is important to recognize that most of the glucose loss in Fl-Ox fasting samples on ice happens within 30 mins of blood draw. 28 This may be due to delayed cooling of Fl-Ox samples impeding the immediate arrest of glycolysis even when samples are rapidly analysed.…”

Different pre‐analytical techniques and the results of 50 g oral glucose challenge tests

“…Accurate measurement of plasma glucose has consequential results for the diagnosis of diabetes mellitus regarding the different cut‐off levels of several diagnostic criteria. Ex vivo glycolysis continues in blood sample tubes until analysis, and this process is affected from the duration until analysis, immediate centrifugation and the room temperature 1,2 . These factors cause a time‐dependent decrease in the plasma glucose levels until analysis.…”