Which additive is used in the gray top tube?

The gray top tube is specifically used for certain tests that require the preservation of glucose and the inhibition of glycolysis. The correct additive in the gray top tube is Sodium Fluoride/Potassium Oxalate. Sodium Fluoride is effective in inhibiting the enzyme enolase, which is a key factor in the glycolysis process, while Potassium Oxalate acts as an anticoagulant by binding calcium in the blood. This combination allows for accurate measurement of glucose levels by preventing their breakdown during the handling and transportation of the sample.

Other additives, such as Sodium Citrate and EDTA, are used in different types of tubes for various tests, but they do not provide the same preservation for glucose testing as the Sodium Fluoride/Potassium Oxalate combination found in the gray top tube. Sodium Citrate is primarily used for coagulation studies, while EDTA is typically utilized for hematological tests, making the gray top tube's specific additive essential for accurate glucose level assessment.