What is the function of the gray tube in blood collection?

The primary function of the gray tube in blood collection is to precipitate calcium and inhibit glycolysis, making it suitable for tests that require accurate measurement of glucose levels. The gray tube typically contains sodium fluoride as a glycolytic inhibitor, which prevents the breakdown of glucose by metabolic processes in the blood sample while maintaining its stability for an extended period. Additionally, it often contains potassium oxalate, which anticoagulates the sample by binding calcium. This is particularly important for tests that require glucose monitoring, as it ensures that the glucose levels remain steady without interference from cellular metabolism.

The other functions described in the other options do not apply to the gray tube. For example, tubes with serum separator gel are used for serum tests, not for glucose preservation. Anticoagulants for clotting tests are found in different colored tubes, typically the blue or purple tubes, while blood gas analysis typically utilizes green or gray-green tubes that contain heparin as the anticoagulant.