What anticoagulant is found in a green top tube?

The correct answer is heparin, which is the anticoagulant found in a green top tube. Heparin works by inhibiting the clotting process, specifically targeting thrombin and factor Xa in the coagulation cascade. This property is particularly useful in various laboratory tests and for collecting blood samples without allowing them to clot, enabling the accurate assessment of blood components.

The green top tube is commonly used for tests requiring plasma or whole blood, such as some chemistry panels that require cellular components to be preserved in their active state. Heparin is widely utilized in both clinical and research settings for its effectiveness and rapid action.

In contrast, other anticoagulants like EDTA, citrate, and oxalate are associated with different tube colors and have specific functions. EDTA, found in lavender top tubes, is often used for hematology tests as it preserves cellular morphology. Citrate, commonly found in light blue top tubes, is primarily used for coagulation studies, while oxalate is used in gray top tubes for glucose testing. Each of these anticoagulants serves unique purposes in the laboratory, which is why recognizing the specific use of heparin in the green top tube is essential for proper blood sample collection and handling.