EDTA and ACD Tubes: What is the Difference Between Them?

When you get a blood test, you might see that the technician uses tubes of different colors to collect your blood. There is a specific reason for each tube. EDTA tubes and ACD tubes are two of the most common types. They might look the same at first, but they aren’t. There is a different type of anticoagulant in each tube. This means that they stop the blood from clotting.

Labs, doctors, and even patients who want to know how their blood samples are handled need to know the difference between EDTA and ACD tubes. We’ll explain it in simple terms in this blog so you can see what makes these tubes different.

Why Do Blood Collection Tubes Have Additives?

Before jumping into EDTA vs. ACD tubes, let’s quickly look at why blood collection tubes need additives at all.

• Blood naturally clots when it leaves the body. This is good when you have a cut, but not good if you want to test the blood in a lab.
• To keep blood in liquid form, labs use tubes that contain anticoagulants.
• Each anticoagulant works differently and is used for specific types of tests.

That’s why labs use many kinds of collection tubes: lavender, yellow, blue, red, green, and more. Each color top means something different.

What is an EDTA Tube?

EDTA stands for Ethylenediaminetetraacetic acid. It is a chemical that binds to calcium in the blood. Since calcium is needed for clotting, when EDTA removes calcium, it prevents the blood from clotting.

Color of EDTA Tube

EDTA tubes are usually lavender (purple) top tubes. In some labs, you may also see pink tops (used mostly for blood bank testing).

Types of EDTA Tubes

1. K2 EDTA tubes

K2 EDTA tubes have dipotassium EDTA inside them, usually in the form of a spray-dried layer that covers the inside of the tube. Many modern labs prefer these tubes because they keep blood cells intact while reducing sample loss to a minimum.

2. K3 EDTA tubes

K3 EDTA tubes hold liquid tripotassium EDTA. Earlier, these were used more often, but now they are not as popular in clinical labs. It’s possible for test results like hematocrit and mean corpuscular volume (MCV) to be affected by the liquid addition weakening the blood sample.

Common Uses of EDTA Tubes

EDTA tubes are widely use in hematology. That means they are used for tests related to blood cells. Some common examples are:

• Complete Blood Count (CBC) – counts red cells, white cells, and platelets.
• Hemoglobin and Hematocrit tests – measure oxygen-carrying cells.
• Blood Smear – looks at the shape and size of blood cells under a microscope.
• Blood Bank crossmatching – pink-top EDTA tubes are use in transfusion labs.

Why EDTA is Preferred for Blood Cell Testing

EDTA is gentle on blood cells. It keeps the size and shape of red and white cells stable for hours. This makes the results more accurate.

What is an ACD Tube?

ACD stands for Acid Citrate Dextrose. It is a mixture of citric acid, sodium citrate, and dextrose (a type of sugar).

• Citrate binds to calcium, stopping clotting.
• Dextrose provides energy to the cells, helping them stay alive longer.

Color of ACD Tube

ACD tubes are usually yellow top tubes. They should not be confused with SPS yellow-top tubes, which are used for blood cultures.

Common Uses of ACD Tubes

ACD tubes are not for routine blood tests. They are use for special purposes, such as:

• DNA and genetic studies – keeps white blood cells alive so DNA can be extracted.
• HLA typing – used in organ transplant compatibility testing.
• Flow cytometry – used for studying immune system cells.
• Special molecular tests – where cell integrity is important.

Why ACD is Preferred for Specialized Tests

Unlike EDTA, ACD preserves white blood cells for longer periods. This is important for tests where living cells or intact DNA are need.

EDTA and ACD Tubes: Side-By-Side Comparison

Feature	EDTA Tube	ACD Tube
Full Form	Ethylenediaminetetraacetic Acid	Acid Citrate Dextrose
Cap Color	Lavender / Purple (sometimes Pink for blood bank)	Yellow
Type of Additive	EDTA (chelates calcium)	Citrate + Dextrose (binds calcium and preserves cells)
Primary Purpose	Prevents clotting and preserves cell shape	Prevents clotting and preserves living cells longer
Main Uses	Complete Blood Count (CBC), blood smear, hematology tests, blood bank crossmatching	DNA and genetic testing, HLA typing for transplants, flow cytometry, molecular studies
Cell Preservation	Maintains cell shape but not long-term cell viability	Keeps white blood cells alive longer due to dextrose
Stability of Sample	Stable for ~6–8 hours at room temperature	Stable for several days
Routine Use in Hospitals	Very common (used daily in labs)	Rare, used only for specialized tests
Not Suitable For	DNA studies needing live cells	Routine hematology or blood counts

EDTA and ACD Tubes: How to Choose the Right Tube for Your Needs

Choosing the correct blood collection tube is important because the wrong one can affect test results. While both EDTA and ACD tubes stop blood from clotting, they are not use in the same way. The right choice depends on the type of test the doctor or lab needs. Here’s a quick guide to help you understand when to use each one:

Use EDTA tubes (purple or pink top):

• For routine blood tests like a Complete Blood Count (CBC)
• When checking for anemia or infection
• For blood bank crossmatching before a transfusion
• Anytime the lab needs to see the shape, size, and number of blood cells

Use ACD tubes (yellow top):

• For DNA and genetic testing where cell preservation is important
• During HLA typing for organ or bone marrow transplants
• For flow cytometry, which studies immune system cells
• When samples need to stay stable for several days instead of just hours

In short, EDTA tubes are best for everyday blood tests, while ACD tubes are for special cases like genetic studies and transplant work. Always follow the lab’s instructions, because using the wrong tube can give inaccurate or unusable results.

Why You Can’t Use Them Interchangeably

It may seem like both tubes stop clotting, so why not use them interchangeably? Here’s why:

• If you use an EDTA tube for DNA testing, the cells may die too fast, and the DNA won’t be good for analysis.
• If you use an ACD tube for a CBC, the blood cells may change shape, making the counts unreliable.

Whether you’re running hematology tests, DNA/RNA studies, or blood banking procedures, KDLNC tubes provide the certified precision and reliability your lab can count on.

That’s why each tube has a specific purpose, and mixing them up can cause errors in results.

Safety and Handling of EDTA and ACD Tubes

Both tubes are safe to handle, but lab staff must:

• Fill the tube to the correct volume, because too much anticoagulant compared to blood can change results.
• Invert the tube gently after collection (usually 8–10 times) to mix the blood with the additive.
• Avoid shaking, which can damage blood cells.

Why Choose KDLNC EDTA & ACD Tubes?

At KDLNC, we understand that accuracy in diagnostics begins with reliable sample collection. That’s why our EDTA and ACD tubes are designed with:

• High-purity additives to ensure consistent anticoagulation.

• Sterile, leak-proof design for maximum safety and sample integrity.

• Internationally certified quality compliance, backed by rigorous documentation and certificates available on request.

• Optimized shelf life to maintain stable results across applications.

With certified manufacturing standards and strict quality assurance, KDLNC ensures every tube meets the requirements of modern laboratories.

Final Thoughts

Choosing the right blood collection tube is essential for accurate lab results. EDTA and ACD tubes may both prevent clotting, but they serve very different purposes. EDTA tubes are best for routine blood counts and cell studies, while ACD tubes are use for specialized tests that require living cells, like DNA analysis and transplant typing. Using the wrong tube can lead to incorrect or unusable results, so understanding the differences is key for labs and patients alike.

Key Takeaways

• EDTA tubes (lavender/pink tops): Used for routine blood tests like CBC and blood smears.
• ACD tubes (yellow tops): Used for DNA studies, HLA typing, and flow cytometry.
• EDTA preserves cell shape but not long-term viability.
• ACD preserves live cells for several days due to dextrose.
• Using the wrong tube can lead to inaccurate or unusable results.
• Color coding matters: Lavender/pink for EDTA, yellow for ACD.
• Follow lab instructions to ensure proper sample collection and testing accuracy.