In this instructional video, the presenter explains the BUN (blood urea nitrogen) and creatinine lab values, their physiological origins, normal reference ranges, and how kidney dysfunction affects their levels. Creatinine, a waste product of muscle metabolism, is filtered by the kidneys; when kidney function declines, blood creatinine rises above the normal 0.6–1.2 mg/dL. BUN, produced by the liver from protein metabolism, is also cleared by the kidneys; impaired renal function raises BUN above the normal 7–20 mg/dL. The BUN:creatinine ratio, normally 10:1 to 20:1, combines these values to help assess kidney health and is linked inversely to glomerular filtration rate (GFR). The video emphasizes the importance of these labs for nursing school exams, directs viewers to a related GFR video, and encourages engagement and confidence in becoming a nurse.
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In this video, we're going to break down what a BUN creatinine ratio is. We will talk about what it all means and what you need to know about the BUN creatinine ratio so you can pass your nursing school exams, my friend. You will be tested on this all the time. So let's dive in. Now, if you haven't figured this out already, the kidneys are a big, big deal, and they impact so many things on the body. You will be testing on them a ton in nursing school. You might already know this. It can be kind of tricky to learn how all of it works. And ties and lab values are a big way that we can check in on the kidneys. And as you probably could guess, the BUN creatinine ratio has two parts, BUN and creatinine. So let's talk about creatinine first. Creatinine is one of the most important, I would say, most important kidney labs that you need to look at. Creatinine is one of those waste products that the kidneys are responsible for getting rid of. So here's how this works. All throughout the day, your muscle cells are constantly building up and breaking down. And creatinine is a byproduct 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 now to make sure we fully understand what creatinine is and really what it does in the body. Now, let's go through critical thinking points and break it all down here, step by step. So what do you think would happen to the creatinine level in the body when the kidneys are damaged? Will it go up or will it go down? It will go up. Since the kidneys are damaged, they can't filter out that creatinine out of the blood. Right. More and more of it will just build up and build up in the blood. So the creatinine level will then increase. A normal creatinine level is between 0.6 to 1.2 milligrams per deciliter. So if that level is much higher than normal, I want you to be thinking there might be something happening here with the kidneys and look into it further. So now that we understand more about creatinine, let's dive into bun. First off, what does BUN stand for? It stands for blood Urea nitrogen. Urea nitrogen is made by the liver. As protein is broken down and metabolized in the body, the liver makes all this urea and nitrogen and sends it out into the blood to then be filtered by the kidneys. A normal blood urea nitrogen, or BU1 level should be between 7 to 20 milligrams per deciliter. So if the kidneys aren't functioning as well as they should be, and the kidneys are responsible for filtering out that waste product, right, that urea nitrogen, what could we expect to happen to the amount of urea nitrogen in the blood? The blood urea nitrogen level will start to increase, right? Just like creatinine. When the kidneys aren't functioning as well, they aren't able to excrete as much of it out into the urine. It gets reabsorbed back into the blood. So that increases the BUN level. So as the kidney function decreases, you will see the BUN and the creatinine levels start to increase as they build up more and more in the blood. As the kidney function declines, they're unable to filter out the creatinine in the blood, so it just builds up in the blood. Same thing with that urine nitrogen. And now the ratio of these two values gives us that bun creatinine ratio. So normally, a bun creatinine ratio should be between 10 to 1 and 20 to 1, which means there should be 10 to 20 times as much bun as creatinine in the blood. Now, remember that creatinine and BUN do the opposite of gfr, or glomerular filtration rate. And that's another kidney lab value that you absolutely have to know for your nursing school exam. So click on this video right here and I'm going to walk you through everything that you need to know about that gfr, that glomerular filtration rate. And if you like this video, write love in the comments below, because that is just our thing around here. And as always, my friend, go become the nurse that God created only you to be, and I will see you over there in that next video.
