What additive is used in the collection of blood specimens for glucose testing?

The choice that accurately identifies the additive used in the collection of blood specimens for glucose testing is sodium fluoride and potassium oxalate. Sodium fluoride serves as a glycolytic inhibitor, which means it prevents the breakdown of glucose in the blood sample. This is crucial for accurate glucose measurement, as any glycolysis that occurs after the blood is drawn could lead to falsely low glucose levels in the test results.

Potassium oxalate acts as an anticoagulant which also helps in preventing clotting of the blood sample. The combination of these two additives ensures that the glucose level remains stable during transport and analysis, allowing for precise testing and reliable results. This is especially important in clinical settings where accurate glucose levels are necessary for diagnosing conditions like diabetes.

Other additives mentioned do not serve this purpose. Lithium heparin is primarily used for plasma determination in various chemistry tests, EDTA is used mostly for hematology tests, and gel activators are used in serum separation but not specifically for glucose testing.