Which type of blood tube contains sodium citrate as an anticoagulant?

The light blue tube is designed to contain sodium citrate as an anticoagulant, which is essential for certain laboratory tests that measure coagulation. Sodium citrate works by binding calcium in the blood, effectively preventing clotting during the testing process. This property is particularly important for tests such as prothrombin time (PT) and activated partial thromboplastin time (aPTT), allowing for accurate measurement of the blood's coagulation ability.

In comparison, the red-top tube does not contain any anticoagulants and is typically used for serum testing where clotting is required. The green-top tube contains heparin, another anticoagulant, but it functions differently than sodium citrate. The purple-top tube contains EDTA, which also serves as an anticoagulant but is used for different purposes, like complete blood counts (CBCs). Each of these tubes has a specific function in laboratory testing, emphasizing the importance of using the correct tube to ensure accurate test results.