Lab Values, part 7: Potassium (K)

Hi, I'm Meris, and in this video, I'm going to be talking to you about the lab value potassium, its function in the body, its expected range, and possible causes and symptoms associated with hypokalemia and hyperkalemia. I'm going to be following along using our lab values flashcards. These are available on our website, leveluprn.com, if you would like to grab a set for yourself. Or if you are more of a fan of digital products, I would invite you to check out Flashables, the digital version of all of our flashcards available on demand and at your fingertips. All right, let's go ahead and get started.

So we are talking about potassium today, and we need to understand what potassium is so that we understand its role in the body. Potassium is an incredibly important electrolyte. It has a job in maintaining the intracellular fluid. So it's very important for our normal cellular physiology that's at play. And it also is incredibly important when it comes to muscle function, specifically cardiac muscle function. So when we're talking about potassium, I want you to know that this is kind of one of those really heavy-hitting electrolytes that you need to know everything about when it comes to not just passing inclines, but also your own clinical practice.

When we are talking about somebody who has an imbalance to their potassium level in either direction, you need to be thinking this is potentially affecting my patient's heart, and that is a very big concern for me. That is my priority body assessment, right? No matter if we're talking high or low potassium. Now, what is the expected range for potassium in the body? The expected range for potassium is going to be 3.5 to 5.0 milliequivalents per liter or mEqs per liter. This is one of those lab values that you just got to learn it, love it, get a necklace that says it. It's never going away. It's one of these things that's going to be with you for life. So we do have a couple of ways to help you remember this incredibly important range for potassium.

The first one that we have here is our cool chicken that reminds you that there are approximately 3.1 miles in a 5K. So that kind of helps you to remember K, 5K, right? K for potassium, 3.1 miles in a 5K. That gives you sort of that range. But remember, we're talking 3.5 to 5. The other, and this is how I remember it, is that bananas come in bunches of 3 to 5. So again, it's not giving you that exact number. You are going to be responsible for remembering that 3.5 number, but it does help you to hone in on the range a little bit there. So if your patient has a potassium level that is lower than 3.5 mEqs per liter, this is a condition known as hypokalemia. I know we really want potassium to be in that word somewhere, but the kalemia is going to come from the K, that is that elemental symbol representing potassium.

So when we're talking about hypokalemia, what are some possible causes here? Well, a big one is going to be diuretic use. And this is one that you just have to know, especially when we are talking about loop diuretics such as furosemide. They drop all those electrolytes, IDE, I drop electrolytes. So we need to be concerned about potential for dropping our potassium level if we are using a diuretic such as furosemide or another loop diuretic. Some other causes would be GI losses. I always think about potassium in my patients who have been vomiting or having severe diarrhea. GI losses are certainly a place that we can see a patient end up with hypokalemia. Cushing's syndrome is another one that you need to know about. This is a very important finding associated with Cushing's syndrome is going to be that hypokalemia. And then metabolic alkalosis. A patient who is experiencing metabolic alkalosis may also be experiencing hypokalemia for one reason or another.

Now, what are my symptoms? Well, if I know that potassium affects my cardiac function, then I should also know that if I don't have enough potassium, something is going to be wrong with my cardiac function, right? Something's not going to be functioning right. So we need to be concerned about dysrhythmias. I'm going to give you a big hint here though, is that dysrhythmias are on the menu if we are talking about hypokalemia or hyperkalemia. It does not matter. We are monkeying around with the function of the heart by having too little or too much potassium. Therefore, dysrhythmias are possible in either direction. Now, some more possible findings associated with hypokalemia, muscle weakness. I don't have enough potassium to give me that muscle contraction and strength that I need, so muscle weakness is possible. Constipation or even a paralytic ileus. If I have muscle weakness, that also affects the muscles of my GI tract. So I will have that slowing down, which can result in constipation or ileus. And then hypotension and/or weak pulses are also possible findings.

Now, on the flip side, if we are talking about somebody with hyperkalemia, this is somebody who has too much potassium, which we would know because they have a potassium level that is greater than 5.0 milliequivalents per liter. This, again, is a very big red flag and should be a red flag to you as a nurse that I need to be concerned. And when we are talking about hypokalemia, we can give potassium. When we're talking about hyperkalemia, we need to figure out how to get rid of potassium. So these are some things that I might be able to advocate for when I'm talking to the provider.

Now, some possible causes associated with hyperkalemia. A big one here is going to be diabetic ketoacidosis, also known as DKA. I want you to immediately recognize, though, that diabetic ketoacidosis is a form of metabolic acidosis, and metabolic acidosis by itself, not just DKA, is another possible finding, another possible cause of hyperkalemia. Use of salt substitutes. Now, when we talk about salt substitutes, we're talking about things that you can buy at the store. This is for somebody who's maybe been told that they've got high blood pressure, and they should avoid salt. So they use a salt substitute. Instead of NaCl, they are actually ingesting KCl. This is going to be potassium chloride. It is also a salt. It is just not sodium chloride. But if I go crazy and I start putting that on all of my food, I'm at risk now for hyperkalemia, okay? Another possible cause here is going to be kidney failure. And I want you to tie this in closely with your patients who are on hemodialysis. Hemodialysis is not a cause of hyper K. It's actually going to help to fix it to bring it down. But if I have somebody who is on hemodialysis, that is because they are experiencing end-stage renal dysfunction, and they need that machine to filter their blood for them. They are experiencing kidney failure. I know that hyperkalemia is a potential problem for them. So it's super important as well.

There's one other that I do want to throw in here, which is diuretic use, but a different kind. If we use potassium sparing diuretics such as spironolactone, we can end up holding on to too much potassium and being hyperkalemic versus furosemide, which will cause us to lose potassium and become hypokalemic. All right, now what are some possible findings in a patient experiencing hyperkalemia? I already told you dysrhythmias, right? We know that we are messing around with cardiac conduction when our potassium goes too high, so dysrhythmias are a possible finding here. We also, of course, have muscle twitching or weakness. Again, we're messing around with how the muscles are functioning, so they're going to not be working exactly right. We might have that twitching or that weakness. Paresthesias, excuse me, such as burning or a numbness and tingling sensation are possible, along with diarrhea. And remember that this may be your body's attempt to get rid of some of the potassium through the GI tract.

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

Which body system is the priority to assess in a patient experiencing a potassium imbalance?

Cardiac.

The nurse is caring for a patient experiencing diabetic ketoacidosis, DKA. Which potassium imbalance should the nurse anticipate?

Hyperkalemia.

Select all that apply. Which of the following are possible causes of hypokalemia? Furosemide use, use of salt substitutes, diabetic ketoacidosis, Cushing syndrome, and kidney failure.

Furosemide use and Cushing syndrome. The others are possible causes of hyperkalemia.

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