Which tube contains EDTA as an additive?

The purple or lavender top tube is used for collecting blood specimens that require the anticoagulant EDTA (Ethylenediaminetetraacetic acid). EDTA works by binding to calcium ions in the blood, which prevents clotting and preserves the integrity of the blood sample for various hematological tests, such as complete blood counts (CBC) and blood smears.

The other tubes do not contain EDTA; for example, the red top tube typically has no additives and is often used for serum tests where clotting is required. The gold top tube usually contains a gel separator and is also used for serum collection, but it does not include anticoagulants like EDTA. The light blue top tube contains sodium citrate as an additive, which is used for coagulation tests rather than preventing clotting through a mechanism similar to EDTA. Understanding the role of each tube's additive is crucial in phlebotomy to ensure accurate test results.