The basics of blood work

Feb 28, 2014

If you're a patient, having your blood drawn for a medical test may be simple for you. But what's done with your blood after it ends up in the tube is probably a big mystery. This week on WRVO's health and wellness show "Take Care," hosts Lorraine Rapp and Linda Lowen, speak with Anne Marie Mullin, senior vice president of Laboratory Alliance, a lab that provides testing to a 16-county region in central New York, to find out more about how blood tests really work.

Lorraine Rapp: So you’re having your blood drawn, and you notice a few things. Each vial has a different color-coded top. Where does that blood go, and what are they actually taking notes on? What’s going on, and why are things being separated right then and there as the blood comes out of your vein?

Anne Marie Mullin: Often times, tests are performed on tubes of blood with caps of different colors, and those caps indicate what is or is not in that tube itself. Some tests are performed on whole blood, so the specimen will be drawn into a tube that keeps that blood from clotting. Other tests are performed on the serum. So those capped colors indicate whether there is something that’s going to allow that specimen to clot, or not to clot, and there are different chemicals in those tubes that allow certain tests to be performed and other tests not to be performed.

Linda Lowen: Once that blood is drawn, how long until it really needs to get to the lab?

Anne Marie Mullin: There are a number of tests that are done in any given laboratory. For example, we perform well over 1,500 tests that are on our test menu. And, depending on the test, it determines how quickly that specimen needs to get to the laboratory. A test, for example if a doctor is looking to perform a pneumonia level, that test needs to get to the laboratory expeditiously, within a short period of time. Some tests can only be performed on a specimen that’s kept protected from light, because light might degrade the substance that we’re looking to measure. Some tests can only be performed at ambient or room temperature. Others have to be kept refrigerated, and some other tests have what is known as critical processing, and perhaps we need to quickly process that tube and freeze it. So, it varies depending on the test name how we have to handle that specimen.

Linda Lowen: What is it that we, as patients, can do beforehand to make our veins easier to access? I heard a lot about drinking water. And what do you on your end to make a blood draw easier for the person with difficult veins?

Anne Marie Mullin: Well there’s not a whole lot you can do to change the way your veins are when you go in to present yourself for a blood draw. But yes, you’re correct, keeping yourself properly hydrated will allow the tissue and the area around the vein to be in a better state so that you can ascertain that vein and quickly go in and draw that patient’s specimen. Warming an arm sometimes will help. Sometimes the phlebotomist will ask somebody to make a fist and pump their arm. That just moves the muscle and the tissue around where the veins are so the veins are a little more visible. But a trained phlebotomist, can usually with a gloved finger feel around and feel where that vein is, and they know where in the center of the arm the veins are typically located.

You can hear more of this interview WRVO's health and wellness show Take Care, Sunday at 6:30 p.m. Support for this story comes from the Health Foundation for Western and Central New York.