CPT (Certified Phlebotomy Technician) Practice Exam

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What chemical additive is in a lavender tube?

Lithium Heparin
Sodium Citrate
EDTA
Silicone

The correct answer is: EDTA

The correct answer is EDTA. Lavender tubes, also referred to as purple-top tubes, are primarily used for collecting blood specimens for hematological tests, such as complete blood counts (CBC) and type and crossmatch procedures. EDTA (ethylenediaminetetraacetic acid) acts as an anticoagulant by binding calcium ions in the blood, effectively preventing coagulation and allowing for better analysis of cellular components in the blood. In contrast, lithium heparin is used in green tubes to facilitate the collection of plasma, sodium citrate is found in light blue tubes and is used primarily for coagulation testing, and silicone is not commonly recognized as a chemical additive associated with blood collection tubes. Each type of tube is designed with specific additives tailored to the requirements of different laboratory tests, reinforcing the importance of using the appropriate tube for accurate and effective testing.