Phlebotomy Technician

Answer: D - Gray-topped tubes may have either potassium oxalate or EDTA & sodium fluoride, or only sodium fluoride. A gray-topped collection tube indicates the presence of additives meant to prevent blood cells from using the glucose present in the sample. Sodium fluoride is an anti-glycolytic, as well as stabilizer. Potassium oxalate and EDTA are anticoagulants. Gray top tubes are gently rotated, about 5 times, immediately after collection. Incorrect mixing may result in blood sample clotting and rejection from the laboratory.