What is the additive found in a gray top tube?

The gray top tube is specifically designed for blood tests requiring certain preservatives to maintain the integrity of the sample. The components found in a gray top tube include sodium fluoride, which acts as a glucose preservative, and potassium oxalate, which is an anticoagulant. Sodium fluoride prevents glycolysis, the breakdown of glucose by cells, thus ensuring that glucose levels remain stable for accurate testing. Potassium oxalate helps to prevent the blood from clotting, which is important for obtaining clear serum or plasma for analysis.

This combination of additives is crucial for tests such as glucose tolerance tests, where accurate glucose levels are essential for diagnosis. The presence of sodium fluoride distinguishes the gray top tube from those with other additives that either do not preserve glucose or serve different purposes in laboratory testing.