What type of tube is used for coagulation testing?

The light blue tube is specifically designed for coagulation testing because it contains sodium citrate as an additive. Sodium citrate works by binding calcium ions in the blood, which is essential for the clotting process. This anticoagulation allows for the accurate measurement of various coagulation factors, such as prothrombin time (PT) and activated partial thromboplastin time (aPTT), without the interference of clot formation.

In contrast, the other types of tubes contain different additives that are not suitable for coagulation studies. The red tube typically lacks any anticoagulant and is meant for serum testing, while the green tube contains heparin, which interferes with coagulation tests. The lavender tube has EDTA as an additive, which is also used for hematology tests but does not provide the specific anticoagulation properties required for accurate coagulation assessments. This is why the light blue tube is the appropriate choice for coagulation testing.