Lab Values, part 10: Troponin T & Troponin I

Hi, I'm Meris, and in this video, we're going to be talking about the lab values troponin I and troponin T. I'm going to be following along using our flashcards here for lab values. All right. Let's go ahead and get started. All right. So in this video, we're going to be talking about two different lab values, troponin T and troponin I. I'm going to be talking to you about them as a group, except for when we are talking about their different expected ranges and when they should peak and how long they should last and all of these things. But here's what I want to get across to you about troponin.

Troponin T and troponin I are both used to examine the muscle of the heart. And what we're doing here is we're looking to see if any troponin T or I, which is a makeup, it is a component, a chemical found in cardiac muscle tissue, is any of that free-floating around in our blood? And the reason we want to know this is because if so, that means that there is some sort of cardiac muscle damage that is going on because troponin T and troponin I are the most specific enzymes that we can examine to see if there has been any damage to the cardiac tissue itself.

So if you come into the hospital and I'm your ER nurse, you tell me that you are having chest pain, at my facility, I have the ability to place an order for a high sensitivity troponin where I'm going to say, "This is part of our protocol order set. I'm allowed to order this under my physician's name because of the fact that this patient is presenting with chest pain." And if that lab value comes back and it is elevated, that says, "Oh, that chest pain just might be because there's something wrong with the heart." Now, obviously, there's other stuff we're going to be doing too. We'll be getting an EKG, we'll be getting a chest X-ray, checking other labs, all kinds of things. But this is a really good marker because if it's negative, if our troponin values come back negative, well, that's a pretty good indicator that the chest pain we're feeling is not related to cardiac muscle damage. So that's why these two lab values are so crucially important, and it's important to know when you are caring for patients so you understand what the role is.

The other thing that I want to tell you about troponin is that it will continue to rise as that cardiac muscle experiences ischemia. So the worse the damage is, the more troponin will be released, and we can trend that. So this is a lab value that in clinical practice, you may see trended, meaning that we're going to draw it every couple of hours. So if you come to me in the hospital saying you have chest pain and that first troponin comes back negative, that's not the only one we're going to do. We're going to repeat that lab value a certain amount of time later to make sure that it is still negative. Because if it comes back and it has started to rise, uh-oh, that's cardiac muscle damage.

Now, let me talk to you about the expected range for these. So first up, we're going to talk about troponin T. The expected range for this one is going to be less than 0.1 nanograms per mL. But again, the point here is that I expect this to be as close to zero as possible because I do not ever expect, it is not the average or the norm for my patient to have cardiac muscle damage, especially acutely. So I expect that that value is going to be low, as close to zero as it can. Now, the specific expected range for troponin I is going to be less than 0.03 nanograms per mL. So a slightly different read there, but the point here again is we are as close to zero as we possibly can be.

Now, let's talk about some of the different ways that troponin is going to work in our blood when it is elevated. So if we do have elevated troponin - excuse me - in our blood, then we are going to be concerned about that. And like I said, especially with a positive result, we are going to trend that. Maybe every four to six hours, we're going to be repeating that lab value. It just depends on what that clinical picture is. Now, with troponin T, here's some important information for you. We expect that it will be detectable within two to three hours. So again, I start feeling chest pain. My troponin isn't going to be elevated immediately. And this is why we wait and redraw a negative troponin on somebody with acute chest pain, two to three hours. It will be peaked within 12 to 48 hours. So sometime in that time zone is when we will see that peak. However, we expect that it's going to start to resolve, and that for troponin T, it's going to be elevated for about 10 to 14 days before it resolves. So that's a pretty good chunk of time. And that's important patient teaching so that if we do have a patient with an elevated troponin level and we discharge them out into the community, "Hey, your troponin T is going to be elevated for up to two weeks. So that's an important thing for you to share with your healthcare provider so that if they're following up on this, right, they know where you are in that window of time."

Now, for troponin I, detected also within two to three hours, peaks also within 12 to 48 hours, so we love and appreciate that. However, with troponin I, it is only elevated for 7 to 10 days. Now, luckily, we do have some Cool Chicken hints here to help you remember the timing of these things. So troponin I looks like the Roman numeral one, right? And it is going to be elevated for about one week, 7 to 10 days. Whereas troponin T starts with a T, and it is going to be elevated for about two weeks, 10 to 14 days, okay? So that is how you can help to remember the difference between how long they will be elevated.

The thing that I really want to get across to you here, though, is that if you are a working nurse, and this is something that you are very familiar with with troponin, there are multiple different types of tests that can be done. Some places use the specific troponin T, troponin I, maybe CK-MB, maybe myoglobin. They're looking at different parts of the muscle, and that's A-okay if that is what your facility does. Your facility may also use something called a high sensitivity troponin, and your facility may not. So it's important that if you are a working nurse and you are refreshing your knowledge here for your own clinical practice, make sure you go back and look at what specific troponin values your facility uses so that you can be up to date and ready to know what those expected values are.

All right, I'm so glad you stayed until the end. I've got some quiz questions to test your knowledge of key facts provided in this video.

The nurse expects which troponin lab value to return to baseline first?

Troponin I.

Which troponin value is used to diagnose myocardial infarction?

Both troponin T and troponin I are the most specific and reliable enzymes used to diagnose myocardial infarction.

True or false, an elevated troponin always indicates that the patient is experiencing an acute myocardial infarction?

False. Remember, troponin I can be elevated for up to 10 days. Troponin T can be elevated for up to two weeks. That patient may not still be experiencing an acute myocardial infarction but may still have an elevated troponin level.

All right, that is it for this video. I hope you found it useful. All right, I'll see you in the next one. Thanks so much, and happy studying.