Which colored tube should be used for a Coagulation test, such as PT or aPTT?

The light blue tube is the appropriate choice for coagulation tests, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT). This specific tube contains sodium citrate as an anticoagulant, which is essential for coagulation studies because it binds calcium ions in the blood. The removal of calcium is crucial to evaluating the blood's ability to clot properly.

Using the light blue tube ensures that the samples are collected in a way that does not interfere with the test results, providing accurate measurements of the coagulation factors. It is also important to note that the tube should be filled to the correct volume, as the ratio of blood to anticoagulant is critical in coagulation testing to ensure reliable results.

In contrast, other colored tubes serve different purposes: the lavender tube is generally used for hematology tests, the green tube is used for some chemistry tests that require heparin as an anticoagulant, and the gray tube is typically used for glucose testing or lactate measurements without affecting the coagulation tests.