Our Handy Guide for Research that Relies on Blood Results
It has happened to all of us at some point. You’ve been working on one project for a while, and there’s a question you can’t answer with your current methods.
So you’ve thought about it, and you’ve discussed your observations with your team, and you’ve all decided that it’s time to add a blood test to the protocol.
Now here you are, sifting through pages and pages of tubes on the internet.
As you’ve surely realized by now, blood collection tubes are highly specialized for use in specific downstream applications.
Blood is a complex tissue type that is used to analyze everything from genetic disease markers to ion concentrations.
For this reason, there are many different ways that you might choose to collect and process it.
Using the wrong tubes can prove disastrous, and it’s easier to do than you might think.
Phlebotomist's Barbie Transport bin, pictured above
Types of Blood Test Tubes:
"Luer lock" is the general term used for the connector that gives vacuum capabilities to rubber capped blood collection tubes.
They create an internal vacuum that moves blood into the tube after the needle enters the vein.
Needles are attached to a tube lock that grasps the head of the blood collection tube. Blood enters the tube freely once the needle is properly inserted into the vein.
Tubes are selected based upon the amount of blood required and the downstream tests being used.
When drawing blood, the container should always be filled at least half of the way to the top when removed. Certain tests require containers to be filled to the maximum.
You can go to this Laboratory Alliance of New York website to view a cheat sheet that tells you what fraction of each tube to fill for each test.
The following list goes over the main types of tubes, their uses, and how to identify them. You will find a more extensive table here on the UNC Health website.
Other clinical web pages and laboratory education sites also provide similar handbooks for blood collection tube selection.
Serum Tubes
Serum tubes are designed to collect the liquid portion of blood without the clotting factors included.
Clotted blood may be used for certain tests too, but the serum must be removed in under two hours.
Appearance: These tubes can be identified by red, red and gray mottled, or gold caps. They may or may not contain particles that assist with clot activation.
Navy Blue caps are also seen sometimes. These are common in drug testing.
Check to make sure that your navy blue capped tube does not have any additives before using it for serum tests.
Additives: None in most. Some contain silica particles to assist with clotting.
Types of Tests used for: Immunology, routine chemistry, and serum testing.
EDTA Tubes
Ethylenediaminetetraacetic acid (EDTA) tubes are used to collect whole blood and preserve it so that it can be processed later.
Appearance: These tubes come with either lavender, purple, or pink caps.
Blood stored in these tubes cannot be used for coagulation tests. Tan capped tubes also exist, primarily used in lead testing.
Additives: Potassium EDTA- EDTA is a chelator that inactivates the thrombin clot formation pathway by making calcium less available as a cofactor.
Additional additives may be found in combination to tailor collection tubes to specific tests, like the addition of polyester in EDTA tubes for PCR tests.
Types of Tests used for: CBCs and blood banking. They may also be used for certain diagnostic tests and flow cytometry.
Heparin Tubes
Heparin tubes are another type used for collection of whole blood and plasma. They prevent clotting by inhibiting thromboplastin and thrombin.
Appearance: These tubes have intense or pale green caps.
Additives: Lithium or sodium heparin- Heparin is an anticoagulant and assists antithrombin in blood and also sequesters calcium.
Types of Tests used for: These tubes are typically used for tests that require immediate attention, like blood ion and gas levels or viral titers.
They may also be used for routine chemistry and genetic screening.
Other Specialized Tubes
Other types of tubes with preservatives meant for assisting with isolation of ions and specific blood nutrients exist.
Sodium citrate tubes: Sodium citrate also chelates calcium and prevents coagulation. These tubes come with a light blue cap and are often used to test clotting factors.
Sodium fluoride and potassium oxalate: These additives inhibit glycolytic enzymes and act as anticoagulants.
The tubes are capped with light gray lids and used for blood glucose testing.
Innovations in Blood Collection Technology
Blood collection tubes continue to improve with changing demands in research and medicine.
You no longer need to manually add anticoagulants and preservatives to samples.
On top of that, tubes now offer option gel separators intended to create a physical barrier between the layers in a centrifuged sample.
Gel separators are not to be used with samples that are designated for drug testing as they may reduce level counts.
As time goes on, suppliers are even beginning to offer specialized rat and mouse blood collection tubes for smaller volume samples.
Stellar Scientific’s Growing Catalog of Collection Tubes
The takeaway here is that blood collection is a lifelong journey for any researcher who chooses to use it in the lab.
For Clinical Diagnostics, it is a way of life. Whatever the reason, make sure you’re getting the best deal from a cost-benefit analysis point of view.
Here at Stellar Scientific, we offer a growing selection of blood collection tubes and accessories. Browse our current catalog of serum tubes and K2EDTA tubes today!
We even have transport buckets and replacement tube caps for the other steps in the process.
Don’t hesitate to reach out to us if you have any questions! Our number and normal business hours are posted on the contact us page.
Footnotes:
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- “Minimum Blood Collection Requirements for Selected Tests.” Laboratory Alliance of Central New York, LLC, www.laboratoryalliance.com/healthcare-providers/l... Accessed 12 July 2024.
- “Blood Collection Tubes.” Blood Collection Tubes - LabCE.Com, Laboratory Continuing Education, www.labce.com/spg263741_blood_collection_tubes.asp... Accessed 10 July 2024.
- “Evacuated Blood Collection Tube Guide | Mclendon Clinical Laboratories.” Edited by J Carr, UNC Health, www.uncmedicalcenter.org/mclendon-clinical-laborat... Accessed 12 July 2024.
- “Specimen Requirements/Containers.” Specimen Requirements/Containers | Department of Pathology | School of Medicine | University of California, Irvine, 25 Jan. 2024, www.pathology.uci.edu/services/specimen-containers...
- Shabnam, I., D S, C., & B C, J. (2014). Ethylenediaminetetraacetic Acid (EDTA) - dependent pseudothrombocytopenia: a case report. Journal of clinical and diagnostic research : JCDR, 8(10), FL03–FL4. https://doi.org/10.7860/JCDR/2014/9603.5019
- Speight MO, Griffith MJ. Calcium inhibits the heparin-catalyzed antithrombin III/thrombin reaction by decreasing the apparent binding affinity of heparin for thrombin. Arch Biochem Biophys. 1983 Sep;225(2):958-63. doi: 10.1016/0003-9861(83)90111-x. PMID: 6625618.