What is the primary test associated with the lavender top tube?

The lavender top tube is primarily used for testing complete blood counts (CBC). This type of tube contains an EDTA anticoagulant, which prevents blood coagulation and preserves the cellular components of blood for accurate analysis. A CBC evaluates various components of the blood, including red blood cells, white blood cells, and platelets, providing essential information about a patient’s overall health, immune status, and potential underlying conditions.

This specific function of the lavender top tube distinguishes it from other types of tubes used for different tests. For example, the coagulation tests like PT/INR typically utilize light blue top tubes, blood cultures are collected in specific culture bottles to detect infections, and ESR tests are generally performed using a different anticoagulant. Therefore, the lavender top tube's role in performing CBC makes it the correct choice for this question.