What is an EDTA (ethylenediaminetetraacetic acid) tube?

From the Guidelines

An EDTA tube is a blood collection tube containing ethylenediaminetetraacetic acid as an anticoagulant, primarily used for hematology tests and procedures requiring whole blood. These tubes are typically identified by their lavender or purple tops and contain EDTA in liquid or spray-dried form at concentrations of 1.5-2.2 mg/mL of blood. EDTA works by binding calcium ions in the blood, which are essential for the coagulation cascade, thereby preventing clotting and preserving cellular components. EDTA tubes are specifically indicated for complete blood counts (CBCs), blood smears, HbA1c testing, and molecular diagnostic procedures including PCR and flow cytometry, as seen in studies such as 1. When collecting blood in EDTA tubes, they should be gently inverted 8-10 times immediately after collection to ensure proper mixing of the anticoagulant with the blood sample. These tubes have limitations, as excessive EDTA can cause cell shrinkage and morphological changes if the tube is underfilled, potentially affecting test results. Blood collected in EDTA tubes should ideally be analyzed within 24 hours when stored at room temperature, though some parameters remain stable for longer periods. It's also important to follow the recommended blood draw order to avoid carry-over additives that may result in inaccurate results, as suggested by 1. Some key points to consider when using EDTA tubes include:

• Using the same brand of tubes consistently throughout studies to reduce variability
• Limiting the number of lots to as few as possible
• Following the recommended blood draw order to avoid cross-contamination
• Avoiding underfilling the tube to prevent cell shrinkage and morphological changes. In terms of specific applications, EDTA tubes are often used for measuring biomarkers such as BNP and NT-proBNP, as seen in 1. However, it's essential to note that EDTA plasma may give a consistent negative bias compared to matched serum samples for NT-proBNP. Overall, EDTA tubes play a crucial role in various medical tests and procedures, and their proper use is essential for accurate results.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Definition and Purpose of EDTA Tube

• An EDTA (ethylenediaminetetraacetic acid) tube is a type of blood collection tube used to prevent clot formation and preserve blood cells for laboratory testing 2.
• EDTA is a polyprotic acid that chelates calcium and other metal ions, preventing blood clotting and allowing for the preservation of cellular components and morphology of blood cells 2.

Types of EDTA and Their Uses

• There are different types of EDTA salts, including tripotassium EDTA (K3EDTA) and dipotassium EDTA (K2EDTA) 3.
• Dipotassium EDTA is recommended as the anticoagulant of choice for blood cell counting and sizing due to its solubility and minimal effect on red blood cell size 3.
• K3EDTA is also commonly used, but it can cause a slight dilution of the specimen and affect red blood cell size at increased concentrations and on storage 3.

Comparison with Other Anticoagulants

• EDTA is compared to other anticoagulants, such as sodium citrate and lithium heparin, in terms of their effects on hematological parameters 4.
• The study found that heparin agreed largely with K3EDTA in the estimation of full blood count parameters, while citrate determined some parameters more accurately and precisely 4.
• Another study compared the effects of different anticoagulants, including EDTA, on selected hemogram parameters and found significant differences between Na2EDTA and K3EDTA 5.

Storage and Handling

• The storage stability of blood samples collected in EDTA tubes can affect the accuracy of laboratory results 5.
• A study found that there was a significant sequential increase of hematocrit and MCV between 1 hour, 8 hours, and 12 hours of storage at room temperature 5.
• Another study found that the use of EDTA plus citrate-theophylline-adenosine-dipyridamole (EDTA-CTAD) as an anticoagulant can reliably assess platelet and neutrophil activation status ex vivo if blood is collected, held at 4°C, and analyzed within 6 hours 6.