Blood Urea Nitrogen (BUN) (Nursing)

00:01 So let's review those test that we'll look at in assessing real disease.

00:05 That's why we're in this video series so you can get a feel for what you can look at and what you'll be evaluating is part of the healthcare team First is the BUN.

00:15 That's Blood Urea Nitrogen.

00:18 We don't often call it the bun, we usually say BUN.

00:21 Now serum creatinine is another lab test will look at.

00:25 So so far we've looked at two lab tests.

00:28 BUN and Serum Creatinine.

00:31 They'll also look at estimating the GFR from the serum creatinine.

00:36 Now that's the glomerular filtration rate.

00:39 It's a really good indication of kidney function.

00:41 And lastly a urinalysis.

00:44 When we say including sediment that is like the whole (shebang).

00:49 We're looking at it visually we're looking at under a microscope.

00:52 We're doing all kinds of tests on this urine to see how the kidneys are functioning.

00:57 So these are four major test that healthcare provider will usually order and the whole team will be evaluating.

01:04 BUN, serum creatinine, estimating the GFR from the serum creatinine and urinalysis.

01:12 Now, I know I've gone through those a couple times because these are for Cornerstone test that you need to be very familiar with.

01:20 Now does the BUN, is it came from a blood test, or from a urine test? Right? It's blood, just as the serum creatinine and then the estimation of the GFR is something that we do as a calculation from the serum creatinine, but the urine analysis is actually looking at urine.

01:40 Let's talk about the BUN, and as urea and renal function.

01:44 This lets us know how your kidneys are working.

01:46 So let's back up and talk about urea.

01:48 Woo, that sounds like fun.

01:50 So Urea is a water soluble nitrogen containing waste product.

01:54 Now, normally your kidneys can filter that out from the blood into the urine.

01:59 So urea is a water-soluble waste product.

02:03 That's the most important point I want you to remember.

02:06 So when we talk about BUN, we're talking about a waste product that is water soluble.

02:12 Now, it's a sign of the kidneys are compromised if you see an increased BUN level.

02:18 Can also be a sign that the patient is dehydrated, but we'll be watching a BUN closely if it's going up and it's elevated.

02:25 Now, we measure this by doing a blood test, BUN, a blood urea nitrogen test.

02:32 Now, these are the normal levels.

02:34 I know, I know there is a lot to memorize the good news is when you're actually actually practicing these values will be printed right alongside what your patients values are because every lab is a little different but we want to give you a normal range reading kind of keep in mind.

02:50 So the only way to remember normal values is just keep looking at them over and over and over again.

02:57 Be sure to quiz yourself on this, because these are important parts of exam questions and your professional practice.

03:05 Okay, so what really does the BUN do, what does it tell us? Well, it's an indication of both your renal function and your liver function.

03:14 Okay.

03:15 Hello.

03:15 Did you catch it? That's pretty cool 1 Test, 2 organ systems that lets us know what's going on as far as the amount of urea nitrogen in a patient's blood sample.

03:27 So again, where does this come from? Well the liver and the kidneys are involved.

03:33 In the liver, makes urea from another waste product.

03:37 Okay. So step one.

03:39 We know that a BUN is the measure of urea in your blood and so it's the blood urea nitrogen content. Right? So we've got that as a lab test.

03:48 We know that urea comes from the liver making it from another waste product.

03:54 Now in case that's confusing stay with me.

03:57 Urea comes from ammonia.

04:00 Now, ammonia is a waste product after the liver breaks down protein.

04:05 So this should kind of start making sense. Right? If you've taken care of a liver failure patient.

04:10 We don't like to give them a lot of protein because they end up turning it into ammonia enough that liver is limping.

04:17 Then the liver can't break it down and turn it into something water-soluble.

04:22 That's a problem.

04:24 So urea normally happens in my body when the liver turns ammonia into urea.

04:31 Okay, so let's walk through how that happens.

04:33 We know that we get ammonia as waste product after the liver breaks down protein in a process called deamination.

04:41 Now, you see look at the molecule we have there for you.

04:43 You've got ammonia, which is NH3, Scott nitrogen and three hydrogen.

04:49 Don't worry, you won't ever have to draw that as a nurse, but we want you to understand how this process works in your body.

04:56 So I eat a steak.

04:58 It's breaking up some protein in my body, end up with ammonia as a waste product from that, what happens next? Well ammonia needs to be converted to urea in order to be excreted into urine.

05:12 So the livers got to turn the ammonia into urea which is water soluble so I can pee it out of my body.

05:20 So it's really important that the liver be able to convert the ammonia to urea in order for me to be able to get rid of it via my pee.

05:29 If I can't, I'm going to have elevated ammonia levels, Now this is really traumatic, If you've ever seen a patient who has a high ammonia level.

05:39 People with liver failure tend to have high ammonia levels because they can't turn the ammonia into urea because our liver is not functioning well.

05:49 Excess ammonia is neuro toxic.

05:52 Toxic is never a good word. Right? Neuro means it's toxic to my brain.

05:58 So impaired livers lead to elevated ammonia levels and that is neurotoxicity.

06:04 This can be life threatening.

06:05 You'll see confusion as the most levels get higher and higher even to the point where the neuro changes are so difficult it can lead to coma.

06:14 So if the body can't convert ammonia to urea the body can't get rid of it excess levels of ammonia lead to neurotoxicity coma and death.