Sodium Heparin is used as an anticoagulant in which color top tube?

Sodium Heparin is used as an anticoagulant primarily in the green top tube. This tube contains lithium or sodium heparin, which prevents blood from clotting during the collection and storage processes. Heparin works by inhibiting thrombin and factor Xa, which are crucial to the coagulation cascade, thus making it suitable for various laboratory tests that require the measurement of plasma or whole blood without the interference of clotting factors.

In contrast, the red top tube lacks any anticoagulants, allowing for clot formation and is typically used for serum tests. The blue top tube contains sodium citrate, which is also an anticoagulant but works through a different mechanism, specifically binding calcium ions and is primarily used for coagulation studies. The gold top tube, on the other hand, has a gel separator and is used for serum tests after the blood has been allowed to clot. Thus, green top tubes are specifically chosen for tests requiring heparin as an anticoagulant agent.