What is the most suitable blood collection tube for glucose estimation?

Objectives Glucose is one of the most frequently measured analytes in laboratories. Most recent studies on glucose stabilities confirm that the sodium fluoride/potassium oxalate (NaF/KOx) tube is far from the gold standard. Citrate tubes have been suggested as the preferred tube type by many institutions. Greiner has introduced a glucose-specific tube (Glucomedics) containing NaF/KOx, citrate, and EDTA to minimise glycolysis. The aim was to determine which tube would be the most suitable for accurate glucose estimation in a routine laboratory setting. Design and methods The study process involved three experiments: (a) participant comparison using lithium heparin plasma as the comparative sample; (b) stability study (0, 1, 2 and 4h); and (c) minimal fill volume for the citrate and the Glucomedics tubes. Results The patient comparison study of lithium heparin plasma showed that EDTA, NaF/KOx, and both citrate and Glucomedics if corrected for dilutional factors produced acceptable results. The stability study up to 4 h showed that the Glucomedics tube was most effective in preventing clinically significant change in glucose concentration at a room temperature. Both citrate and Glucomedics need to be filled within 0.5mL of the recommended fill volume for acceptable results. Conclusion The Glucomedics tube is the most suitable for minimising glycolysis. Further improvements to it (use of correct dilutional factor and the addition of gel separator) would make this tube the benchmark for the most accurate estimation, best diagnosis and patient care decisions.