Dear Dr. Toshi, (Lab Results Part 3)
I went to see my doctor, and she showed me my lab results, but I had no idea what they mean. Can you explain them to me?
Today I'll talk about the last part of the Complete Blood Count lab (CBC), namely, platelets. Basically, platelets play an important role in repairing injuries and clotting blood. So, I'll talk a little bit about blood clots, too.
Platelets are disk-shaped cells in the blood which play many roles, but most importantly, they help stop bleeding when your blood vessels are damaged. Platelets change their shape and work with other substances in the blood to cause blood clots to form. When you cut yourself, you see a scab forming, and platelets play a key role in that process. When people don't have enough platelets, they have a hard time stopping bleeding.
Platelets are in the blood, in both the arteries and the veins. In normal circumstances, when someone starts bleeding, platelets help stop the bleeding. But this can be a problem because this same process can also cause blood clots that are harmful.
Before going into details, let me explain some words you might hear at your doctor's office or your medical provider's office. The medical word for a blood clot is "thrombus." When a thrombus forms in a blood vessel and then breaks loose and is carried by the blood and gets stuck in another part of the body, it's called an "embolus." You might have heard of a "Deep Vein Thrombosis" (DVT) or a "Pulmonary Embolism" (PE). "Pulmonary" means the lungs.
A few weeks ago, when I talked about red blood cells, I talked about the blood vessels as pipelines to and from the heart. We have two sides to this bloodstream: arteries and veins. The heart pumps blood with oxygen out to the body through arteries. Red blood cells in your bloodstream carry oxygen o destinations all over the body, just like a bus carries people to different destinations. Where are those destinations? They are the different parts of your body, such as your brain, kidneys, intestines, skin, muscles, and even your heart and lungs (yes, even the heart and lungs need oxygen to function, too!). Oxygen are dropped off at those destinations through the capillaries, which are the smallest arteries in the body. In the capillaries, oxygen is dropped off, and carbon dioxide and other wastes are picked up by the red blood cells and brought back to the heart through the veins.
The story is a little bit more complex because you might wonder where these red blood cells pick up oxygen. In order to explain this, I'll talk about our heart a little more today. You probably know that the heart is a pump that pumps the blood, but did you know that it's actually two pumps? The right side of your heart pumps blood to your lungs, and the left side of your heart pumps blood to your body. To explain in a little more detail, blood coming back through the veins to your heart has a lot of carbon dioxide but little oxygen, and it comes into the right side of your heart, which pumps it out to the lungs. In your lungs, the blood dumps out the carbon dioxide (which you exhale), and picks up oxygen (which you inhaled), and then that blood with a lot of oxygen goes to the left side of your heart. The left side of your heart pumps it out through the arteries to your body, where it supplies oxygen to your body's cells. This cycle continues as long as your heart is beating. Can you picture that? Uff da!
The reason I'm talking about this today is because I want to make it clear that blood clots in arteries and veins end up in different places, and they're also formed differently. In arteries, cholesterol plays a big role in building up plaques on the inside walls of your arteries, and those plaques damage your arteries. Plaques (also called "atherosclerotic plaques") are buildups of fats, cholesterol, and other substances on the arterial walls. Plaques are bad, of course, because they narrow the arteries and restricting or blocking blood flow, but what's even worse is that they can also burst open. When this happens, platelets come to try to fix them, but that can cause blood clots to form. If these blood clots are dislodged, they can be carried downstream to other places in your body such as your brain (which we call a stroke) or your heart (which we call a heart attack).
On the other hand, a deep vein thrombosis (DVT) is a blood clot in a vein, as the name suggests. It's different from a blood clot in an artery because a blood clot in a vein can form without damaging the vein. DVTs tend to form in the legs most often, and there are a number of things that can increase your risk of getting a DVT, such as dehydration, being overweight, injuries, surgery, smoking, birth control pills, diseases like cancer, and simply being inactive (such as sitting for a long time in a combine, semi, tractor, swather, airplane, car, etc.). Our risk also increases as we get older. We don't want to be dehydrated because that makes the blood thicker, so blood clots can form more easily. If you get a blood clot in a vein and it breaks off and goes into your bloodstream, it can go up to the right side of your heart and get pumped out to your lungs, where it gets stuck and blocks the blood flow. That's called Pulmonary Embolism (PE), and it can be life-threatening.
So, avoiding blood clots is one reason why it's good to stay hydrated, eat healthy food, not smoke, and be active!
Dr. Toshiko (Toshi) Luckow, MD is a Family Medicine physician at the West River Health Services hospital and clinics.