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The Connection Between Platelets and Bruising

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Published on October 1, 2021

How Are Platelets and Bruising Connected?

Is there a connection between platelets and bruising? Watch as Andrew Schorr, co-founder of Patient Power and CLL patient advocate, discusses this topic with Susan Leclair, PhD, CLS (NCA), Chancellor Professor Emerita at the University of Massachusetts Dartmouth. Dr. Leclair describes platelets by comparing them to the structure of a loofa.

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Transcript | The Connection Between Platelets and Bruising

Andrew Schorr: Hello, and welcome to Patient Power. I'm Andrew Schorr in San Diego. Joining me from Dartmouth, Massachusetts, is a laboratory science blood cell expert. That's Dr. Susan Leclair. So Susan, some of us are told we have lower platelets and we bruise. What are platelets, and what's the connection with bruising?

What Are Platelets?

Dr. Leclair: Platelets are pieces of a cell. They're not a whole cell in themselves. They come from an extremely large cell that sits in the bone marrow that, like one of the characters in Alice in Wonderland, starts breaking off pieces to the edge and those edges are platelets. They're very, very small, and they look kind of funny in that sense. When you look at them, it looks like... It's the closest I could get... They look like a sponge or that they look like one of these bath washing thingies.

They've got all of these edges to them, which means they've got a lot of surface area. When that surface area comes upon a broken blood vessel, it sticks onto that broken blood vessel, and the rest of it sticks on that broken blood vessel. So, it contorts itself with all of this extra cytoplasm around the edge to making a variation of the Dutch boy with his finger in the dike.

These single platelets will then cause other platelets to come along and bind with it. So instead of having one there, you might have a whole patch of platelets, like 30, or 40, or 100 of them all stuck together. For the vast majority of our lives, banging your hand on the table or that kind of very small, you didn't recognize what it was, damage to blood vessels those platelets are sufficient. They're just available for you. When it gets bigger, when the damage isn't just one spot on a capillary, but maybe is an inch long or is a gash of some sort, these things need something else to support them, and those are the proteins of the coagulation system.

Usually for people who have got underlying disease, the coagulation system's not a big deal so I'm not really going to talk about it. But there is that system. When you look at this thing, which does twist and turn quite elaborately, if I only have five of them and I need 50, I'm not going to make a pretty good plug. I'm going to make a small and insufficient one. Very small damage will create those little, tiny dots that you... Some they're red, they look like a freckle, they'll have that. Those are called petechiae and usually, 90% of the time, it's because there aren't enough of these.


I'm on aspirin. I can have plenty of these, but they don't work as well as they should. They won't stretch and rearrange themselves to interact with other ones the way normal ones can. Mine are going to stay around. So, if I happen to have [a] damaged blood vessel in which one of these can perfectly plug in, because it's not going to change shape, then I'm okay. But if I get a gash, a long one, this is not going to work, and it's not going to be able to bring enough platelet packing material into that area. I'm going to get petechiae, those small round blood vessels.

Andrew Schorr: But let's make it bigger. So some of us get purple bruises. So what's happened then? Not just petechiae, but it's like a big purple spot.

When Does Bruising Occur?

Dr. Leclair: Yeah. It's flat, and it's bright red and it's always where you don't want it to be. Those are called ecchymosis. You don't really need to know the names, although you may hear them. It's just that there are three different kinds. That's the big issue. The flat ones, the bright red ones that eventually turn multi-colors, the ones that have uneven edges. What's happened there is probably a combination of damage between the platelets and that clotting process that I mentioned. You can get some plugging. So these can work, but not enough. So, you end up with a... This is a bad example. You end up with a lacy kind of clot instead of a solid one. So, if it's got openings in it, blood can continue to ooze out.

So what an ecchymosis is, is blood continuing to leak out through a less than quality clot. Women have more of these than men do normally. Why? Because women have more estrogen than men do, and estrogen causes you to have more surface blood vessels. That's why we have rosy cheeks when we were at least younger. So what happens as a woman bangs her hand up on something, she gets a bigger damage because the blood vessel is closer to the surface, less well supported, and so this stuff leaks out. As you age, the supporting tissue goes away. You get wrinkles. When you get those wrinkles, you get blood that can leak out between the skin level and the area where those blood vessels are. So you get this spreading. It's flat, it's red, and it has uneven sides. That's a combination of platelets and some of the clotting processes. Does that make sense?

Andrew Schorr: Yes. Some of us have not just fewer platelets, but platelets that are not so healthy. So where does that come in? Blood cancer patients in particular, could be others, where that affects bruising and even bleeding.

What Is the Relationship Between Bruising and Platelets for Blood Cancer Patients?

Dr. Leclair: Go back to this thing. If the only thing this thing can do is bounce off the screen, doesn't stick, doesn't hold, can't adhere for whatever reason, then you could have a two-inch gash in your leg and the platelets will go by saying, "Oh, look, there's a gash," and won't be able to adhere. Since they're the very first part of clotting, if they don't work, then the rest of the clotting process doesn't work as well.

Andrew Schorr: Okay. So to extrapolate from that then, while we have blood tests and it gives us a number.

Dr. Leclair: Yeah, we're good at numbers.

Andrew Schorr: For our platelets. The number is not enough of an answer. It's about the quality of the platelets within that number.

Dr. Leclair: Now we are very good... This is a rare phenomenon to me to say this, but we are very good at testing for the functionality of one aspect of the platelets. It's called Von Willebrand factor. We know a lot about it. We can test for it. We can decide whether or not your function is correct. We can't, however, test for the function say of adhesion, of this ability for this platelet to stick onto something. We have no good tests for adhesion. We've got some tests for some of the other functions of the platelet. But in general, we don't do function tests well on platelets. It's very frustrating because you can look at people... There are some conditions that have extremely high platelet counts. So, the physician and the patient want to know, "Am I risk for super clotting?" The answer is, "I don't know. Why don't we watch it for three months and see what happens?” And if you come back after three months and you've not had a clot or you've not had bleeding, then we can answer that. But there's no real standardized, comfortable way to test for that function.

Andrew Schorr: Wow. Okay. So thank you for explaining platelets. I get it about the bruises I have that I haven't had the whole response, like there's some leakage going on. If I cut myself shaving, there hasn't been enough of response to stop it now with lower platelets or maybe less competent platelets than I had when I was younger.

Dr. Leclair: Which means that your instinct is correct. When you nick yourself shaving, you usually do this or you put alum on it. Either one. What are you doing? You're trying to make the cut smaller. The longer you hold it, the more the seven platelets that you've got can get up there to do their work. So the holding longer, the keeping more pressure on it, that kind of stuff all helps to encourage your platelets to work.

Andrew Schorr: Okay. A critical part of our blood. Dr. Susan Leclair, thank you for explaining that, and we'll let you take your sponge and put it back wherever it goes in your house. Thank you so much for being with us.

Dr. Leclair: You're very welcome. Any time.

Andrew Schorr: I'm Andrew Schorr. Now we understand platelets better. Remember, knowledge can be the best medicine of all.

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