What is the additive found in a light blue tube?

The additive found in a light blue tube is sodium citrate. This anticoagulant is primarily used for coagulation studies because it works by binding calcium in the blood, which is essential for the coagulation process. By preventing the blood from clotting, sodium citrate allows for accurate results in tests such as prothrombin time and activated partial thromboplastin time. The light blue top tube is standardized for these types of assays, making it crucial for obtaining reliable data in hemostasis testing.

Other additives listed in the choices would not be appropriate for a light blue tube. Sodium fluoride and potassium oxalate, for instance, are found in gray top tubes and are used primarily for glucose testing and other specific assays. Ethylenediaminetetraacetic acid, commonly known as EDTA, can be found in lavender top tubes and is used for hematological studies as it prevents clotting by binding to calcium. Lithium heparin, found in green top tubes, acts as an anticoagulant for various tests but does not pertain to the light blue tube's purpose. Understanding the specific use and additive of each tube type is essential for phlebotomy practice.