02.01 Troponin I
- Troponin I
- Normal value range
- Special considerations
- Elevations in lab values
- Normal value range
- Typically less than 0.035 ng/mL or less
- Can vary among institutions
- Has to be greater than the 99th percentile
- Troponin is released during myocardial cell damage
- Decreased perfusion causes myocardial cell damage
- Causes of myocardial cell damage
- Myocardial infarction
- Demand ischemia
- Renal failure
- Extreme exercise
- Special considerations
- Submitted in green top tube
- Value peak
- Detection 6-12 hours after acute injury
- Peaks 24 hours after injury
- Can stay elevated for a week
- Knowing patient history is critical
- Increased values
- Any elevated value is typically considered critical
- Acute elevations warrant immediate investigation
- Typically PCI (percutaneous coronary intervention)/Angiography and EKG to rule out MI or ACS (acute coronary syndrome)
- Other elevations
- Extreme exercise
- End Stage Renal Failure
- Assess for:
- Acute chest pain
- Symptoms of MI
- Angina in any form
- Reflux (especially in women)
- Angiography or PCI
- Management of non-cardiogenic etiology
- Lab Values
- Educate patient on keeping history of elevated levels or cardiac disease for future reference
- Educate patient on duration of elevated troponin levels, post injury
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In this lesson we’re going to take a look at troponin I and what that means for your patient.
Before we get started on the ins-and-outs of troponin it’s really important to understand what the normal value is. The normal value is going to be less than 0.035 nanograms per milliliter. Now, different labs have different troponin assays, or tests, that they do, and the “normal” values can vary. What you need to do is figure out what “normal” is where you are, and what the cut off is. So for all intents and purposes you should consider anything greater than 0.035 high, and we’re going to look at the ins-and-outs of that.
Now order to get a better understanding of why we look at troponin, let’s look at what troponin is is. Well, troponin is a protein found in cardiac and skeletal muscle. What happens is when the cell is damaged is troponin is released into the bloodstream and it’s therefore detectable. So when you have cardiac cell damage, or myocardial necrosis, you’re going to have that increase of troponin in the blood. Now why does myocardial cell damage happen? Well it happens because of decreased perfusion to the heart tissue.
So let’s quickly recap so we’re are all on the same page. If you have decreased perfusion, or decreased oxygenation, to heart tissue, the heart tissue dies, and troponin is released.
So the next question should be when does decreased oxygen to heart tissue occur? Well you’re typically going to see this in a couple of cases, and the big one is myocardial infarction, or heart attack. To understand the ins-and-outs of an MI really well, please go check out that lesson. The other time you’re going to have decreased oxygen to the heart is going to be with something called demand ischemia. And what that means is that you have a decrease of oxygen, which is the ischemia, as a result of high demand. There are reasons for this that are either cardiogenic in nature, meaning that they originate from the heart, and then there are also cases where they aren’t heart-related. And we’ll go into some of those a little bit later in the lesson. But the big takeaway here is that if your heart isn’t getting oxygen, the heart tissue dies, and then you’re going to have an increase and release of this troponin into the bloodstream.
So what do we need to know about the lab itself?
Well first off when you get the blood, you’re most times you’ll submit it in a green top tube which has Heparin in it.
If your patient has only had chest pain or heart attack for maybe less than an hour your troponin levels may not be high, and you’re going to have to recheck them usually every eight hours after a suspected heart injury. You’re going to see detection in about 6 to 12 hours after the injury and it can peak usually around 24 hours. And it can stay elevated for about a week.
Okay, so you’re taking care of your patient, and you get an increased troponin back from the lab. Remember it’s anything greater than 0.035. Anytime that you have an increased value of troponin, it’s almost always considered a critical lab. That means that there’s some sort of heart injury that has occurred or is still occurring and you have to figure out what’s going on. Usually the first thing you’re going to do is you’re going to check on an EKG, you may have to take them to the cath lab to do what’s called a PCI or a percutaneous coronary intervention, or sometimes you have to do angiography to figure out what’s going on and see if there really is a blockage.
I want to encourage you to also pay attention to what’s going on with your patient. If your patient is having your typical heart attack symptoms, so chest pain, it could radiate, any nausea or vomiting, and in women it could feel like reflux, if your patient is experiencing any one of those things and your troponin is high, you need to figure out what’s going on with your patient.
Now there are other instances where you are going to have increased troponin levels. So if your patient has had was called a CABG or a coronary artery bypass graft, and we commonly referred to them as bypass or heart bypass surgery, you can sometimes have some slight elevation in your troponin then. In some extreme athletes, so people that do marathons are Iron Man’s, they may actually have elevated troponin but it’s a small percentage and the troponin elevation is pretty minimal. You also see it in sepsis or even in stage renal failure, And you can also see it in cases of acute coronary syndrome, or any sort of issue where the heart is just not receiving enough blood and oxygen. Again that goes back to your demand ischemia, so if you have a condition that’s putting extra stress on the heart you can have slight elevations in troponin then.
But the big thing here is that if you have an increased troponin, and your patient is symptomatic for an MI, or you suspect they’re having heart attack, you need to act quickly and figure out what’s going on with your patient.
For our troponin lesson, we really focused on the nursing concepts of lab values and perfusion and making sure that the heart gets the oxygen that needs.
Okay so let’s recap.
Elevations in troponin mean that there is cardiac cell damage. It doesn’t always have to be super high, but any sort of cellular damage at the heart level can release the troponin into the bloodstream and it becomes detectable.
0.035 is the cutoff, and anything higher than this is considered a critical value.
Again your facility standards are going to vary depending on the type of assay the lab uses, so check with your facility on what your standard is.
Troponins are going to be detectable at 6 to 12 hours after the injury and it usually peaks within 24 hours. It can also last for up to a week so it’s important to know your patient’s history as well.
If it’s acute, you need to find out why does elevations are happening. You want to make sure that your patient’s not having heart attack, and if they are you want to make sure that you treat them quickly.
So that’s it for a lesson on troponin. Make sure you check out all the resources attached to this lesson. Now, go out and be your best selves today. And, as always, happy nursing!!