Which of the following is a common use for a gray-top tube?

The gray-top tube is specifically designed to manage and preserve glucose levels in blood samples. It contains sodium fluoride, which acts as a glycolytic inhibitor, preventing the breakdown of glucose by red blood cells after collection. This attribute makes the gray-top tube particularly suitable for blood glucose testing, ensuring accurate measurements of glucose levels in the sample. When a sample is required for accurate glucose analysis, the use of the gray-top tube is essential, as it avoids false low results that could occur if glucose were to metabolize after collection.

The other choices do not align with the intended use of a gray-top tube. For example, a CBC (Complete Blood Count) test typically requires a lavender or purple-top tube due to its EDTA anticoagulant, which is optimal for hematological studies. Lipid panels are commonly collected in a red-top or gold-top tube, as these tubes allow for serum separation without the interference from preservatives present in the gray-top tube. Coagulation studies usually utilize a light blue-top tube containing sodium citrate, which is essential for proper coagulation testing. Thus, the association of the gray-top tube with blood glucose testing reflects its unique properties designed for that specific purpose.