Lab Values, part 8: Sodium (Na)

Hi, I'm Meris, and in this video, I'm going to be talking to you about the lab value sodium. I'll be explaining to you its function, the expected range, and possible causes and symptoms associated with hyponatremia and hypernatremia. I'm going to be following along using our lab values flashcards. These are available on our website, leveluprn.com, if you want 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.

All right, so what is sodium? Sodium is an electrolyte that is important for nerve and muscle function, but it also plays a crucial role in regulating our fluid balance. So when I think of sodium disturbances, I think of two different patient populations. I think of patients with neurological concerns. And then I also think about patients who have some variety of fluid imbalance, whether that is fluid volume overload or deficit, there will be an associated sodium imbalance. So that's kind of where I start off when I'm thinking about these things. Now, the expected range for sodium is going to be 136 to 145 mEqs/L or milliequivalents per liter. This is a very specific range, so we gave you a Cool Chicken hint here to help you remember it, which is that, when you shake a salt shaker, you will get approximately 136 to 145 grains of salt, NA. This is just to help you remember kind of what ballpark am I looking for. This, again, is one of those electrolytes that is one of the heavy hitters that you need to know for NCLEX and for your clinical practice. So this is one of those lab values that I would strongly encourage you to commit to memory, even if your school doesn't require you to memorize these.

All right. So if we have too little sodium in our blood - we have fewer than 136 mEqs/L - we call this condition hyponatremia, too little salt in the blood. When we are talking about somebody with hyponatremia, one of the possible causes here is going to be diuretic use, especially loop diuretics. When we are using a loop diuretic, we often drop electrolytes, and that includes sodium. Another thing I want to mention here is that where sodium goes, water will follow. Sodium is a water magnet. So if I'm trying to get rid of water, I may also kick out sodium on purpose with a medicine that is designed to do that. Some other possible causes of hyponatremia here are going to be, kidney failure, diaphoresis, so excessive sweating where I'm losing that salt water, right, to the atmosphere. SIADH, which is, syndrome of inappropriate antidiuretic hormone. In this condition, we end up holding on to way too much fluid, and we end up diluting down the sodium that we do have. We are very, very fluid volume overloaded. Go watch a video about SIADH if you want more information on that. We have a great one about it.

Hyperglycemia, and this is something I want to call your attention to if you are a working nurse, if you ever see a patient with a sodium level of 125, and you think, "Oh, oh my gosh. Oh, no." Check their glucose really quick, just look over there. You probably are looking at their BMP or their CMP. There should be a glucose level there, look at their glucose. Is it elevated? If they've got a blood glucose level that's high, that is probably causing that falsely low sodium level to appear. Then heart failure or any sort of fluid volume overload, we're going to end up with what we call diluational hyponatremia. This means that it's not a salt problem. We've got the right amount of salt. It's that we have so much fluid that we are diluting that salt out. It appears as though our sodium is low. Now, what are some possible symptoms associated with this? What might I observe? Well, when we think of sodium, NA, we also need to think of N for NA and for neuro. Confusion is a possible finding associated with hyponatremia, and it's very common in elderly patients. So keep a look out for that. Fatigue, nausea and vomiting, headache, and seizures are also possible symptoms. When we are talking about sodium and thinking about its impact on brain, brain function, brain swelling, fluid balance, all of that. I need you to think about the priority intervention of implementing seizure precautions. It doesn't matter if we're talking high or low sodium, either way, my patient is at risk for seizure, and I need to be prepared.

Now, if my patient has an elevated sodium level and here we are talking about a sodium above 145 mEqs/L, we call this hypernatremia, more sodium in the blood than expected. Now, what are some possible causes associated with hypernatremia? Kidney failure is going to be one. Excess sodium intake, if I'm eating a lot of salty foods, I'm putting more salt into my body. So if my patient tells me that they've recently taken up a love of salty licorice, well, maybe they have hypernatremia, and that's a real thing that actually has happened. There's a case study that I read about it one time. Cushing's syndrome is another possible one. And this, again, when it comes to Cushing's syndrome, you just got to know all of those electrolyte imbalances. Diabetes insipidus, diabetes insipidus, I have the opposite problem of SIADH. Instead of holding on to a lot of fluid, I'm getting rid of all my fluid. I am passing massive amounts of dilute urine. So as a result, the sodium that sticks around, it's going to look like it is elevated because there's nothing diluting it down. I hope that makes sense for you there. And then fever, with fever, I'm actually going to burn off some fluid due to that elevated temperature. I'm going to have an elevated metabolism, so I can have that high sodium level as well. And then NPO status, if my patient hasn't been eating and drinking, then they're not getting that fluid volume replacing their blood plasma and can appear to have elevated sodium levels.

Now, what are some symptoms associated with hypernatremia? The big one is going to be thirst, and I always just think about this as like I ate a bunch of potato chips. Right? I have a bunch of salt, and I am thirsty, "Oh, gosh, give me something to drink. Right?" If your patient is complaining of thirst, they could be experiencing hypernatremia. Lethargy and confusion, again, we're talking about that impact on the brain, so confusion, again, is a concern. GI upset, muscle twitching, seizures - I already told you that - and then irritability and agitation. So if you're seeing some kind of neuro change in your patient, I want you to take that seriously. A change like that is a symptom, not a behavior, until proven otherwise. So if I have somebody who's suddenly irritable, they're agitated, they're confused, they're not acting right. Maybe I need to check and see, "Ooh, have they been NPO for a while because they're waiting on tests or procedures? Maybe we need some IV fluids on board. Right?" And this is why you do receive IV maintenance fluids if you are not able to eat or drink while you are in the hospital.

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 my quiz questions.

What is the priority nursing intervention for a patient experiencing a sodium imbalance?

Implement seizure precautions.

The nurse is caring for a patient with an elevated glucose level. Which sodium imbalance should the nurse anticipate?

Hyponatremia.

Which sodium imbalance should the nurse anticipate when caring for a patient experiencing diabetes insipidus?

Hypernatremia.

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