Which tube is designed to prevent clotting by using lithium heparin?

The green top tube is specifically designed to prevent clotting using lithium heparin as an anticoagulant. Lithium heparin works by inhibiting thrombin and Factor Xa, which are essential components in the clotting cascade. As a result, blood collected in a green top tube can be processed for tests that require plasma free of clotting elements, making it suitable for various biochemical assays.

The other tubes mentioned do not use lithium heparin as their anticoagulant. The gray top tube typically contains sodium fluoride and potassium oxalate, which are used for glucose and lactic acid testing. The gold top tube contains a gel separator and is often used for serum tests, allowing the blood to clot before centrifugation. The lavender top tube contains EDTA as the anticoagulant, which is mainly used for hematology tests but works differently compared to the heparin-based tubes. Understanding these distinctions is crucial for proper sample collection and handling in phlebotomy.