24 Mar Tube Colors and the Tests They Are Used For
Phlebotomists become very familiar with the colored tubes used for blood collection because they handle them every day. Even though they might know the proper order to use them, they might not always know what each tube tests. Depending on where you work, the request sheet might only mention the color needed, the additive inside, or the lab department it’s headed to. If you’re a phlebotomist curious about the tests you’re drawing for or a patient wondering about your blood test, this article is here to help. We’ll explain what the different colors mean and the tests associated with each.
Blood Culture Bottles
Blood culture bottles are always drawn before any colored tube. They usually come in pairs, filling the aerobic bottle first and the anaerobic second. These bottles contain a growth medium and an anticoagulant, which makes them the best option for:
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- Fungal Cultures
- Bacterial Cultures
Light Blue Top Tube
The light blue top tube has sodium citrate. This stops the blood from clotting, which is crucial for coagulation studies where preventing clotting is necessary, including:
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- Prothrombin Time/International Normalized Ratio (PT/INR)
- Partial Thromboplastin Time (PTT)
- Fibrinogen
- Anti-Xa
- D-Dimer
- Thromboelastography (TEG)
Red Top Tube
The red-top tube sometimes has no additive or might contain a clot activator. This helps your blood clot naturally before the serum is separated. Red tubes can be used for tests that need serum. However, gold tubes are generally preferred for serum tests, so red tubes are often used for specialized tests or as discard tubes.
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- Serum Tests
- Therapeutic Drug Monitoring
Gold Top Tube
Also known as a Serum Separator Tube (SST), the gold-top tube has a gel that separates the serum from cells after spinning it. It’s great for tests that need serum quickly, like:
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- Basic Metabolic Panel (BMP)
- Comprehensive Metabolic Panel (CMP)
- Liver Panel
- Lipid Panel
- Thyroid Stimulating Hormone (TSH)
- Hormone Levels
- Infectious Disease Tests
- Vitamin Levels
- Serology Tests
Green Top Tube
Green top tubes contain heparin, an anticoagulant perfect for plasma or whole blood chemistry tests. These are very common in most facilities. Green tubes are vital for tests that need plasma separated right away, such as:
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- Arterial Blood Gases (ABG)
- Ammonia
- Troponin
- Ionized Calcium
Lavender/Purple Top Tube
Lavender or purple top tubes have EDTA as an anticoagulant. This binds calcium to stop clotting. They cover a wide range of tests to diagnose and monitor conditions, including:
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- Complete Blood Count (CBC)
- Hemoglobin A1c
- Erythrocyte Sedimentation Rate (ESR)
- Sickle Cell Screen
Pink Top Tube
Similar to lavender but for blood bank use, the pink top tube has EDTA. These tests ensure blood transfusions are safe and help manage the blood supply, including:
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- Blood Typing
- Crossmatching
- Antibody Screening
Gray Top Tube
The gray top tube contains potassium oxalate/sodium fluoride, specifically for glucose and lactate testing. These additives keep glucose levels stable until they can be analyzed, useful for tests like:
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- Fasting Blood Sugar (FBS)
- Glucose Tolerance Test (GTT)
- Lactic Acid
- Blood Alcohol Concentration (BAC)
Royal Blue Top Tube
Royal blue top tubes are made for tests that look for tiny amounts of things in your blood. These tubes can have EDTA inside, or they can be empty. They make sure your blood test doesn’t pick up any extra stuff from the tube that could mess up the results. This is super important for:
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- Heavy Metals
- Mineral Levels
- Micronutrients
Yellow Top Tube
There are two kinds of yellow top tubes. One is for DNA and paternity testing, and the other is for specialized immunology tests. These are key for:
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- ABO Group
- Rh Type
Resources for You
If you’re looking for a certain test that is not listed here, there are many online resources to find information on which tests use which tubes. Some will even include what tubes to use if you don’t have the one you need. Here are some useful links to get you started:
Remember, every medical facility has its own specific rules and protocols, so it’s important to always follow the guidelines where you work. Always check with your lab to ensure you use the correct tubes for each test.
Conclusion
In conclusion, every test tube holds vital health information. Whether for managing illness, diagnosing diseases, or preparing for surgery, choosing the right color is crucial in healthcare. This guide aims to demystify the blood collection process, helping both healthcare workers and patients better understand the testing process.