Nursing educator Christina Rafano explains creatinine clearance, a test that measures how well your kidneys filter waste. Normal values run 90–120 mL/min, but the test requires a precise 24-hour urine collection starting after the patient voids and ending exactly at 24 hours. Decreased clearance signals kidney damage.
Hey there, friend. My name is Christina Rafano from nursingschoolofsuccess.com and in this video we are going to talk about creatinine clearance. Yeah, I know you're confused by it because I was too in nursing school. So let's break it down and be sure to stick around until the very end of the video because of course, I've got a free cheat sheet for you to help you out with lab values in nursing school. Alrighty. So creatinine is just a big fancy word for trash. Okay? But it's not exactly trash. It's just a waste product that your muscles make when they work hard all day. So as you move around and go throughout your day, your muscle cells are constantly building up and breaking down and building up and breaking down in order to stay healthy. And when muscle breaks down, it releases creatinine. So creatinine is just a waste product of muscle metabolism. That's all. That it. Now here's where things get interesting. The kidneys are fully responsible for getting rid of all this creatinine. So their job is to take it all out of the blood and excrete it into the urine. So let's walk through some critical thinking here. What do you think will happen to the creatinine level if the kidneys are damaged? Well, will they be able to get out as much creatinine from the blood as they were before? No, sir, they can't. If they're damaged, they can't do their job as well to get rid of all that creatinine. So the creatinine level will build up and build up inside the blood. Now this is why we measure creatinine clearance. It's primarily to check for kidney function. Creatinine clearance is mostly a test of the kidneys and it tests the glomerular filtration rate, meaning how long does it take for the kidneys to get rid of all that creatinine? So creatinine clearance is a really good test for kidney function. It shows us how well the kidneys are doing. Alright. So typically, how we test for this is a 24 hour urine collection. So over the course of 24 hours, you'll collect the patient's urine. Now, here's a key point I want you to know. You've gotta know this in nursing school, it's almost guaranteed to show up on one of your exams somewhere. When you do a 24 hour urine collection, you must have the patient void first before you start and then 24 hours later, you need to collect that last urine right at the 24 hour mark. So when you go to start the creatinine clearance test for a patient, are you going to walk into their room and collect their urine right then and there? No. No, you're not, because the 24 hour clock has not started yet. You will need to have them use the bathroom first and then that starts the 24 hours and you'll collect all of their urine for that 24 hours. You're just trying to get it as precise as possible within that 24 hour time frame. And if you collect that urine that they made before the 24 hours started, the results would be off. So that's why it's super important. Now, typical creatinine clearance is between 90 to 120 milliliters per minute, roughly. And of course that varies for men and women. And it also may decrease with age. So there are some things that can increase or decrease the creatinine clearance value. So let's walk through some critical thinking with these ones as well. So creatinine clearance may increase if someone eats a whole lot of meat and protein or maybe does a lot of weightlifting, because that's building up muscle and building up muscle and the creatine levels inside the blood. So obviously creatinine will be higher and therefore the creatinine clearance will be higher. Now, a decreased creatinine clearance would happen in kidney disease or kidney impairment because like we said before, if the kidneys are damaged, they can't do their job. And because their job is to get rid of that creatinine, if they're damaged, they can't do that. So that creatinine clearance value would decrease. Now, the same goes for dehydration, where the kidneys just aren't getting enough blood flow and there might not be enough fluid to pass through into the urine. Then in that case, you also might see a decreased creatinine clearance as well. So basically, if the kidney might possibly be impaired in any way, most likely you'll see a decrease in creatinine clearance and that is creatinine clearance for you. So now I put a link in the description below this video to your free lab value cheat sheet and be sure to check out all the other lab value videos and med surg videos we have to help you out in nursing school. And as always, friend, hit that like button. Share this video with your friends who might also need some help with creatinine clearance. And of course don't forget to subscribe and hit that bell so you never miss out on a video. Thank you so much for watching. Now go become the nurse that God created only you to be, and I'll catch you right back here. Next time on the nursing school show, take care of.
