Medical Assistant Certification (MAC) AMCA Practice Exam

The role of EDTA, or ethylenediaminetetraacetic acid, found in the lavender tube is primarily to act as an anticoagulant. This means that it prevents blood from clotting by binding to calcium ions in the sample. Calcium is essential for the coagulation process; thus, when EDTA sequesters these ions, it inhibits the cascade of reactions that would typically lead to clot formation.

This property makes EDTA particularly useful in various hematological tests where whole blood analysis is required, such as complete blood counts (CBC). By maintaining the blood in its liquid state, accurate measurements of the various components of blood, including red and white blood cells and platelets, can be obtained.

The other choices present different functions that are not applicable to the role of EDTA in the context of blood collection.