Uses of Purple Top Tubes:

1. Complete Blood Count (CBC): One of the most common tests performed with blood from a purple top tube is a CBC. This test gives information about the number and types of cells in the blood, including red blood cells, white blood cells, and platelets.
2. Blood Smears: This is often done in conjunction with a CBC. A small drop of blood is spread thinly onto a microscope slide and is examined under a microscope. It provides valuable information about the shape and form of blood cells.
3. Hemoglobin Electrophoresis: This test is used to diagnose different types of anemia, specifically those related to abnormal hemoglobin structures like sickle cell anemia.
4. Flow Cytometry: This is a more specialized test that analyzes the characteristics of cells in the blood.
5. HLA Typing: This test is often used in transplant medicine to match donors and recipients.

EDTA as an Anticoagulant:

• EDTA works by binding to calcium in the blood, preventing the blood from clotting.
• Since it preserves the shape of cells, it is ideal for tests that require microscopic examination.
• However, it’s essential not to overfill or underfill the tube as this might alter the blood-to-anticoagulant ratio, potentially leading to erroneous results.