Which top color is used for a glucose-related test such as a glucose tolerance test?

Which top color is used for a glucose-related test such as a glucose tolerance test?

• A. Red topped
• B. Lavender topped
• C. Gray topped
• D. Green topped

Answer: (C)

For glucose-related tests, preserving the glucose level in the sample is crucial because cells can rapidly metabolize glucose after collection, leading to falsely low results. The gray-top tube contains sodium fluoride, a glycolysis inhibitor, plus potassium oxalate, an anticoagulant. The fluoride blocks the glycolytic enzymes, preventing glucose from being used up, while the oxalate keeps the blood from clotting so plasma can be used for analysis. This combination makes gray-top tubes the best choice for a glucose tolerance test, where accurate glucose measurements over time are essential. Other colors lack the glycolysis inhibitor or are intended for different tests, so they aren’t ideal for preserving glucose.

For glucose-related tests, preserving the glucose level in the sample is crucial because cells can rapidly metabolize glucose after collection, leading to falsely low results. The gray-top tube contains sodium fluoride, a glycolysis inhibitor, plus potassium oxalate, an anticoagulant. The fluoride blocks the glycolytic enzymes, preventing glucose from being used up, while the oxalate keeps the blood from clotting so plasma can be used for analysis. This combination makes gray-top tubes the best choice for a glucose tolerance test, where accurate glucose measurements over time are essential. Other colors lack the glycolysis inhibitor or are intended for different tests, so they aren’t ideal for preserving glucose.