In this video, we’re diving into the renal lab values that you MUST know for nursing school.
The kidneys are a big deal and you will be tested on them a TON in nursing school. But it can be kind of tricky to learn how it all works.
So I’m going to give you an easy breakdown of the renal labs you absolutely MUST know, along with some critical thinking points to help you understand how it all fits together.
I’m giving you all the answers in this video! 🙂
HERE’S A BREAKDOWN OF WHAT WE’LL TALK ABOUT:
Glomerular Filtration Rate (GFR) (1:20)
Creatinine (3:00)
Blood Urea Nitrogen (BUN) (5:00)
VIDEO TRANSCRIPT
In this video, we’re diving into the renal lab values that you MUST know for nursing school. The kidneys are a big deal and you will be tested on them a TON in nursing school. But it can be kind of tricky to learn how it all works. So I’m going to give you an easy breakdown of the renal labs you absolutely MUST know, along with some critical thinking points to help you understand how it all fits together. I’m going to give you all the answers, so hit that subscribe button and click the notification bell and let’s dive in.
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The first thing you need to understand about the kidneys is they are one big filter. It’s their job to filter out and get rid of waste products and excess fluid from the body. Without the kidneys, toxic waste products would build up in the blood and cause a lot of problems. And it’s SUPER important for you to know how to tell when something is wrong with the kidneys, and what it all means. So let’s walk through the lab values you’ll need to look for.
Now don’t worry, I have a free lab values cheat sheet to give to you that has the normal ranges listed for the most common lab values you need to know about in nursing school. We’ll put the link in the description for you to download it, and be sure to print it off for clinical because it will be super helpful for you!
So the first lab value we’ll talk about is the GFR, or glomerular filtration rate.
The GFR is the amount of blood the glomeruli (which are little filters inside the kidneys), can process in one minute. When the glomerular filtration rate is good, somewhere between 90 to 125 milliliters per minute is considered normal, that means the glomeruli are filtering 90 to 125 milliliters of blood per minute.
But if the kidneys are damaged, that number will start to decrease, since they can’t filter as much or as fast as usual. It’s also important to point out though that the GFR will naturally decrease with age, so an older patient will naturally have a lower GFR, so that needs to be taken into consideration as well.
Now here’s a critical thinking point I want you to remember:
- If the kidneys are damaged and some of the glomeruli aren’t able to filter as much, the remaining healthy glomeruli will step up their game and try to compensate.
So, if you have a patient whose kidneys are compromised, you might notice that their GFR is still within a normal range, even though the kidneys are damaged. As the damage continues and more glomeruli can’t function, you’ll see the GFR start to decline.
If you’re a NursingSOS Member and want to know more about kidney function and renal disorders, head on over to your membership dashboard and check out the renal/GU course we have for you. In there, I walk you through all the disorders and help you critically think through them all. It’s super helpful, especially as you go take your exams!
Now, let’s talk about creatinine.
This is one of the most IMPORTANT kidney labs you’ll need to look at. Creatinine is one of those waste products the kidneys are responsible for getting rid of. All throughout the day, your muscle cells are constantly building up and breaking down. And creatinine is a bi-product of this natural muscle breakdown. So as it’s released, it travels through the blood and to the kidneys to be filtered out into the urine. So when we test for creatinine, we’re testing for the level of creatinine in the blood.
So here’s your critical thinking point:
- What do you think will happen to the creatinine level when the kidneys are damaged? Will it go up or down? I’ll give you a minute to think about it, I know you can do it!
It will go UP! Since the kidneys are damaged and they can’t filter that creatinine out of the blood, more and more of it will just build up in the blood. So the creatinine level will INCREASE.
So a normal creatinine level is between 0.6-1.2 miligrams per deciliter. So if that level is higher than normal, I want you to be thinking,
“Hmm…There might be something happening with the kidneys.”
And look into it further.
Now the next lab value is another super important kidney lab, but before we get there, I want to give a shout out to Juli for our YouTube comment of the week, which says
“I LOVE the way you explained it. Made it so much easier to understand THANK YOU!”
YAY! I’m so happy it all finally clicked for your Juli! I know learning so much in nursing school in such a short amount of time can be tough, so I’m glad that we can help condense it for you and explain it all in a way that makes sense. That’s what we’re here for!!
I love reading your comments each week, friend. They make me very happy and I feel so blessed to have your support, so thanks for being here!
Now as promised, the next lab value we’ll talk about is another really important renal lab, and this one is called blood urea nitrogen (or BUN for short).
Typically, when you hear of kidney labs being drawn, these 2 go hand in hand: creatinine and BUN.
So, along with creatinine, there’s another waste product that the kidneys usually filter out, and that one’s called urea, or urea nitrogen. Urea nitrogen is made by the liver as protein is broken down and metabolized in the body. So the liver makes all this urea nitrogen and sends it out into the blood to be filtered by the kidneys. A normal blood urea nitrogen level should be between 7-20 miligrams per decileter.
Now, let’s practice those critical thinking skills again:
- What do you think will happen to the BUN level if the kidneys are damaged? Go ahead and think about it for a second…
If kidney function declines, the blood urea nitrogen level will start to increase, since the kidneys aren’t able to function as well and excrete as much of it out into the urine. So as the glomerular filtration rate slows down, you’ll see the BUN start to increase because it’s building up more in the blood, rather than being excreted into the urine. Makes sense, right? If the kidneys aren’t functioning, that urea nitrogen will build up in the blood and so the BUN level will increase.
Now, remember that creatinine and BUN do the opposite of GFR if the kidneys are damaged. The creatinine and BUN levels will INCREASE, but the GFR will DECREASE when the kidneys are damaged.
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