Which additive is commonly used in tubes for glucose tests?

Sodium Fluoride/Potassium Oxalate is the correct choice for tubes used in glucose testing because it serves a dual purpose in preserving glucose levels and preventing glycolysis. Glycolysis is a metabolic process that breaks down glucose, and if blood samples are not processed quickly, the glucose can be significantly reduced due to this process. Sodium fluoride acts as a glycolysis inhibitor, effectively stopping the breakdown of glucose for a period of time. Potassium oxalate functions as an anticoagulant, preventing blood from clotting, which is essential for accurate testing of glucose levels in the sample.

In contrast, other additives do not fit the specific needs for glucose testing. Heparin is an anticoagulant often used in other types of tests but does not preserve glucose. EDTA is typically used for hematological tests and can interfere with glucose testing. Citrate, which is effective in coagulation studies, is not appropriate for glucose measurements as it can also affect glucose levels. Thus, Sodium Fluoride/Potassium Oxalate is the most suitable choice for ensuring accurate glucose testing by preserving the sample from changes in glucose concentration.