Which color tube is commonly associated with Sodium Citrate residue testing?

The color tube commonly associated with sodium citrate residue testing is blue. This is due to the fact that sodium citrate is an anticoagulant used primarily in coagulation studies, such as PT (Prothrombin Time) and aPTT (Activated Partial Thromboplastin Time) tests, where it prevents blood from clotting during the testing process.

The blue tube typically contains sodium citrate as its additive and is essential for correctly performing these tests because it ensures that the blood sample remains in a liquid state, allowing for accurate measurement of clotting factors. Maintaining the proper ratio of blood to sodium citrate is crucial, as an inappropriate ratio can lead to erroneous results.

The other tubes, such as the green (which contains heparin as an anticoagulant), red (which usually has no additives or may have clot activators), and yellow (which often contains additives for blood culture or certain tests), do not have the same properties and would not be suitable for testing requiring sodium citrate. Thus, the blue tube's specific properties make it the correct choice for sodium citrate residue testing.