Which tube should a medical assistant use to draw a blood glucose level on a patient?

The gray top tube is the appropriate choice for drawing a blood glucose level because it contains sodium fluoride and potassium oxalate, which serve specific purposes. Sodium fluoride acts as a glycolytic inhibitor, which helps prevent the breakdown of glucose by cells in the blood sample. This is crucial for accurately measuring glucose levels, as any glycolysis occurring after the blood is drawn could result in falsely low glucose readings. The presence of potassium oxalate also serves as an anticoagulant, allowing for the separation of plasma for further testing.

In contrast, the red top tube is often used for serum testing without any additives, which would not preserve glucose levels effectively. The blue top tube typically contains citrate, which is used primarily for coagulation tests and would not be suitable for glucose analysis. The green top tube, which contains heparin anticoagulant, is used for various tests including blood gas analysis, but it does not provide the same safety against glucose degradation as the gray top tube. Hence, the gray top tube is specifically designed for reliably testing blood glucose levels.