Question

Glucomedic tube and their chemical composition prevent in glycolysis in blood

Answer 1

The most recent guidelines for laboratory analysis in the diagnosis and management of diabetes mellitus recommend that to minimize glycolysis, the sample tube should be placed immediately in ice water slurry, and plasma should be separated from the cells within 30 min. If that cannot be achieved, a tube containing a rapidly effective glycolysis inhibitor, such as citrate buffer, should be used for collecting the sample. Tubes with only enolase inhibitors, such as sodium fluoride, should not be relied on to prevent glycolysis [1]. This recommendation reflect upon the inability of sodium fluoride to inhibit glycolysis effectively.

Fluoride inhibits enolase, which is far downstream in the glycolytic pathway. Enzymes upstream of enolase remain active and continue to metabolize glucose until substrates are exhausted. The antiglycolytic action of fluoride is delayed for up to 4 h and has little or no effect on the rate of glycolysis during the first 1–2 h after blood is collected. Glucose levels can fall as much as 10 mg/dL during this period [2]. Transport on ice slurry and rapid separation of serum within 30 min can inhibit glycolysis without the addition of sodium fluoride and in fact works better as shown by few studies [3, 4]. But this would be impractical to expect that every sample be cooled and separated soon after collection. An effective inhibitor of glycolysis is required to enable to laboratories to estimate true glucose levels in blood.