Let’s talk about common laboratory tests this week, starting with the complete blood count (CBC). A CBC is one of the most routine tests that physicians order but it can also be one of the most important. The four major components of a CBC are the hematocrit, hemoglobin, leukocytes, and platelets. Hematocrit and hemoglobin are both measures of the amount of red blood cells in your blood. Red blood cells are the oxygen carrying cells that carry the oxygen that you breathe in through your lungs to all of the tissues of your body, an essential function because your cells can metabolize (use for fuel) the energy that you eat without oxygen, at least not for very long. Every cell in your body has miniature power plants called mitochondria that utilize a chemical reaction involving oxygen to power everything that your body does from the beating of your heart, to the muscles that are moving your computer mouse, to the brain cells that are sending neuroimpulses to one another as you read my blog! A deficiency of red blood cells is called anemia and we’ll talk about that in the near future.
Leukocyte is a fancy term for white blood cells, the cells that fight off infections from the bacteria, viruses, and fungi that we are all exposed to all day, every day. It’s a little bit disturbing to think about, but you’re breathing in all of these bad guys right now, being exposed to them all of the time in fact, and the reason that we all are healthy most of the time is that our white blood cells, our leukocytes, constantly kill off the bad bugs that are trying to set up shop in our bodies. A deficiency of leukocytes can be seen in people who are really sick with chronic diseases or who have cancer. An elevation of leukocytes can tell your doctor that you may have an active infection because the body naturally produces and releases higher levels of leukocytes when it needs more of them to fight off a nasty pathogen.
Finally, platelets are the blood cells that are responsible for forming blood clots. Every time you cut yourself with a razor or get a small scratch and you don’t bleed to death from it you have your platelets to thank. While platelet clots are usually a good thing, sometimes clots can form in places where we don’t want them, like in the coronary (heart) arteries, for instance, causing heart attacks. Overactive platelets can be treated with medications that inhibit them and aspirin is the most common of these medications—this is the reason why most people who are at high risk of having a heart attack are told by their doctor to take aspirin. Some people also have a deficiency of platelets that places them at high risk of bleeding and these people often need specialized medical treatments, especially in situations that place them at high risk of hemorrhage, like when undergoing a surgery or a tooth extraction.
So a little routine blood test can tell you a lot and we’ve just barely scratched the surface. Tune in next time for “The Electrolyte Panel.”
Dr. Leonardo Noto
Author: Medical School 101, Intrusive Memory, The Life of a Colonial Fugitive, and The Cannabinoid Hypothesis.