Advertisement

Why is so much blood drawn for different blood tests?

William Lee Dubois
Endocrinology Diabetes & Metabolism
Don’t you just love it when they roll a stainless tray over to your elbow and there are six different test tubes on it? Well, if you look closely next time, you’ll find that each one has a different color of cap. The tubes are designed for different blood tests. Some have anticoagulant agents inside the tube so the blood doesn’t clot. Others have special preservatives. Some tubes get put in a centrifuge so that the blood can be “spun” to separate the plasma from the blood cells. Some are kept at room temperature, some are chilled, some are frozen.

If your doctor's ordered a battery of tests on you, you can end up needing to fill quite a few tubes. For those of you who have never had a blood draw before, don’t freak out. Usually, numerous tubes can be filled with a single needle “poke.” A special holder, often attached to a “butterfly” needle, can be used to fill many tubes from a single needle stick. The venipuncture sometimes hurts at the moment it takes place, but once the needle is in the arm, most people don’t feel any discomfort.

Continue Learning about Blood Basics

Step Up: Take Your Blood Pressure Meds and Save Your Life
Step Up: Take Your Blood Pressure Meds and Save Your Life
Q: How can I convince my husband to take his high blood pressure medicine? Help! Katie J., Sioux Falls, SD A: Katie, you’re right to be concerned—un...
Read More
Uncle Sam Needs You! To Donate Your Blood
Uncle Sam Needs You! To Donate Your Blood
Giving blood to people who desperately need it is an essential part of modern medicine. The first documented vascular transfusion came in 1667 when a ...
Read More
What are the types of blood lipids and what do they do?
Healthy HumansHealthy Humans
The first blood lipid test that everyone is most familiar with is total cholesterol. This tells us t...
More Answers
Can I donate blood if I have a skin disease?
American Red CrossAmerican Red Cross
You may donate blood as long as the skin over the vein to be used to collect blood is not affected. ...
More Answers

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.