Green top blood tube is typically used for which type of test?

• A. Test- Hematology
• B. Test- Immunology
• C. Test- Coagulation
• D. Test- Chemistry

Answer: (D)

Green-top tubes contain lithium heparin, an anticoagulant that prevents clotting so the blood remains as plasma. This makes them ideal for chemistry tests that measure enzymes, electrolytes, metabolites, and other chemical constituents, since plasma can be analyzed directly without the need to wait for clot formation or to convert the sample to serum. Hematology workups rely on preserving cellular components, which is typically done with EDTA in purple (lavender) tubes, not heparin. Coagulation studies require a citrate tube to preserve clotting factors for accurate clotting times. For many immunology tests, serum or plasma may be used depending on the assay, but for routine chemistry determinations, the green-top tube is the go-to choice.