What type of blood test typically requires a lavender cap tube?

The lavender cap tube is specifically designed for hematology tests, and one of the most common uses for this type of tube is for a complete blood count (CBC). The additive in lavender cap tubes, which is usually EDTA (ethylene diamine tetraacetic acid), acts as an anticoagulant, preventing blood from clotting. This is essential for a CBC because the test evaluates the cellular components of blood, including red blood cells, white blood cells, and platelets, which can only be accurately measured in an unclotted sample.

While coagulation studies (which often require blue-top tubes with citrate) and blood chemistry tests (which typically use serum tubes with red or tiger-top caps) are important, they do not utilize the lavender cap tube. Blood culture tests, on the other hand, are done in specialized culture bottles designed to detect microbial growth, not in lavender cap tubes. Therefore, the complete blood count is the correct association with the lavender cap tube due to its specific role in blood cellular analysis.