Which additive is present in a gray top tube?

The gray top tube is designed for specific testing requirements, and the additives present in this tube play crucial roles in preventing glycolysis and ensuring accurate test results for certain blood analyses. The correct answer, which identifies sodium fluoride and potassium oxalate as the additives in the gray top tube, highlights their functions well.

Sodium fluoride acts as a glycolysis inhibitor, which is essential for preserving glucose levels in the specimen by preventing its breakdown by cells. Potassium oxalate serves as an anticoagulant, effectively preventing blood from clotting. This combination is particularly useful for tests that require precise measurements of glucose levels, such as glucose tolerance tests, as well as for maintaining the integrity of lactic acid measurements.

Understanding the unique functions of the gray top tube's additives is important for phlebotomy practice since proper tube selection based on the intended test is critical for generating reliable lab results.