What blood tube is needed for glucose measurement and what colour is the tube?

• A. EDTA purple top
• B. Fluoride oxalate and yellow
• C. Heparin green top
• D. Sodium citrate blue top

Answer: (B)

To get an accurate glucose reading, you must stop the cells in the blood from consuming glucose after collection. The way to do this is with a tube that contains a glycolysis inhibitor and an anticoagulant: sodium fluoride acts as the glycolysis inhibitor, and potassium oxalate keeps the blood from clotting. This fluoride-oxalate combination preserves the glucose level long enough for analysis. The color coding of tubes can vary by manufacturer, but the essential requirement is the fluoride-oxalate mix, not the exact color. Other common tubes use EDTA, heparin, or citrate for different tests and do not prevent glycolysis, leading to inaccurate glucose measurements. Therefore, the option describing fluoride oxalate is the correct choice.