Introduction to Creatinine Clearance Test (Nursing)

00:01 Hi! Welcome to our lab series In this one, I'm going to help you understand the difference between urine creatinine and creatinine clearance and how that can help you keep your patients safe.

00:12 Now let's do a quick review.

00:14 Okay, so we're talking about a creatinine clearance test.

00:17 But what is creatinine? Remember it's a waste product when your muscles burn protein for energy, you end up with creatinine.

00:26 Now create an can build up in the blood stream.

00:28 You got to remove it from the body, right? That ends up going out in your urine when we're talking about a creatinine clearance test, we're talking about how effectively your body does that.

00:39 Now let's go back to a little bit of your body parts, there see their picture on the screen.

00:43 Now, what I'd like you to do is just take your finger and put it on one of the kidneys, you can pick whichever one you want.

00:50 Because the job of the kidneys, these healthy kidneys are to filter and remove creatinine from the blood.

00:56 Now it's going to carry that down to the bladder and exit through the body.

01:00 So what I'd like you to do is put your finger on the blue vessel.

01:05 Now, it moves through the kidney goes through the nephron and then it sends it down to the bladder to leave the body.

01:13 So I want you to have that concept because creatinine clearance depends on a lot of things.

01:17 You have to have a healthy kidney.

01:19 You have to have good blood flow.

01:21 So those are some concepts that we're looking at assessing when we're looking at a creatinine clearance test.

01:28 Okay so now we're up to this test.

01:29 Let's give you the official definitions for that.

01:32 A creatinine clearance test is measuring your kidneys ability to filter and remove creatinine your bloods got to get through that kidney and as it's moving through the kidney, this test will tell us how well it's filtering and removing the waste products that we want it to.

01:49 Now correct me clearance test takes more than just a blood sample.

01:53 You need a 24-hour urine sample and that's kind of a big deal because it takes a lot of people participating to make sure we get the right sample, but you need a 24-hour urine sample and you compare it with a venous sample or a blood sample.

02:08 So that's the two things that you need for a creatinine clearance test.

02:12 You both a special urine sample 24 hours, full 24 hours not more or less, but right exactly at 24 hours and a venous sample.

02:24 So being able to compare these two will help us see how well your kidneys are filtering and removing that from your blood.

02:32 Now we're talking about normal levels of creatinine.

02:35 You already know when we're speaking of creatinine, the muscles are involved, right? It's a waste product from the muscles and their energy production.

02:43 So men tend to have a little bit higher muscle mass.

02:47 That's why their normal levels for creatinine clearance is 97-137.

02:52 Females tend to have a little less muscle mass and so their levels are also little lower 88 to 128.

03:01 So how do we measure it? Well, we usually measure with, you already know, we had measure it with both the urine and the blood sample and we can also estimate it.

03:10 Now why would we estimate it? Well, it's back to that 24-hour sample.

03:14 That's a little problematic.

03:16 You have to have the patient pee, then you start the sample at a certain time.

03:19 You have to make sure that it stays cold and you get every sample in between, that's not as convenient as doing an estimation.

03:26 So we can use this fancy in math.

03:28 I like to call it's really not that fancy.

03:31 But we use a mathematical formula and that'll help us estimate the same thing.

03:36 We can do the creatinine clearance.

03:38 Now, you have to figure some things in, you see on your notes there, It says the formula includes age, race, and gender that's because there are differences based on the patient's age, race, and gender.

03:50 We know that males have higher muscle mass than females.

03:53 We know as you age your creatinine levels go up and certain races also have higher levels.

03:59 So let's look at the formula and before you get excited, don't worry about it.

04:03 If you're a math nerd, lock on have at it plug your stuff in there.

04:07 But for the rest of us mere mortals just know this is what it looks like.

04:12 This is an example of one of the formulas that can be used to estimate creatinine clearance.

04:18 Now, here's a keynote I always want to remind students about, remember you this formula only works creatinine clearance only works if the serum creatinine is stable.

04:29 So that's a key point.

04:30 Also sounds like come up as a test question, but remember creatinine clearance is only accurate if their serum creatinine is relatively stable.

04:40 Okay now for women if I want to adjust this formula for women, I would just multiply it by 0.85 and I would get the accurate number for a female.

04:49 Cool, Alright, so we see a formula, don't worry about it.

04:53 You don't have to do the math just know that we can do the math and it'll be calculated for you in a hospital setting or in a clinical setting.

05:02 What you do want to take away from this is most important the serum creatinine has to be relatively stable in order for this to work.

05:10 Women are going to be a little bit lower.

05:12 And remember this just reminds us of the different factors age, gender and race will also be included in that.

05:21 Not in the actual numbers, but it's included in the reporting results.