For which test is the gray top tube primarily used?

The gray top tube is primarily used for glucose tolerance tests because it contains sodium fluoride, which acts as a glycolytic inhibitor. This means it prevents the breakdown of glucose by cells, allowing for accurate measurement of glucose levels in the blood over time. In the context of glucose tolerance testing, maintaining the integrity of glucose levels is crucial, as it provides essential information about how the body processes sugar and aids in the diagnosis of conditions like diabetes.

While the other tests mentioned have specific tubes suited to their purpose, they do not utilize the gray top tube as effectively as glucose tests do. For instance, coagulation tests usually require blue top tubes, while blood type tests are typically conducted using red or pink top tubes. Complete blood count tests are best performed with lavender or purple top tubes. This specificity highlights the role of the gray top tube in glucose metabolism studies and emphasizes its importance in phlebotomy practices related to glucose testing.