Which additive is in the Lt Blue Tube used for coagulation testing?

Which additive is in the Lt Blue Tube used for coagulation testing?

• A. None
• B. EDTA
• C. HEPARIN
• D. Sodium Citrate

Answer: (D)

Sodium citrate is the additive used in the light blue top tube for coagulation testing. It works by binding calcium in the blood, which is essential for the clotting process, so it prevents premature clotting and preserves the plasma for accurate measurement of clotting times. Maintaining the correct blood-to-additive ratio (about 9:1) is crucial; if the ratio is off, the test results can be skewed. After collection, calcium is added back in the lab to initiate clotting for the assay, allowing tests like PT and aPTT to be performed. Other common additives serve different purposes—EDTA is used for CBCs, heparin for some plasma chemistries, and tubes with no additive aren’t suitable for coagulation testing.

Sodium citrate is the additive used in the light blue top tube for coagulation testing. It works by binding calcium in the blood, which is essential for the clotting process, so it prevents premature clotting and preserves the plasma for accurate measurement of clotting times. Maintaining the correct blood-to-additive ratio (about 9:1) is crucial; if the ratio is off, the test results can be skewed. After collection, calcium is added back in the lab to initiate clotting for the assay, allowing tests like PT and aPTT to be performed. Other common additives serve different purposes—EDTA is used for CBCs, heparin for some plasma chemistries, and tubes with no additive aren’t suitable for coagulation testing.