Introduction to Urine Specific Gravity Test (Nursing)

00:00 Hi, welcome to our video series on interpreting lab values.

00:05 We're going to take a look at urine specific gravity.

00:08 Now, it is way cooler than it sounds, I promise.

00:12 Stick with us through the whole series, and we'll show you how this little number can tell you some pretty interesting things about your patient.

00:20 In fact, we can even diagnose some endocrine disorders, along with some patient assessment, if you understand how urine specific gravity works.

00:30 So stick with us.

00:31 Let's start with an overall introduction, but stay for the whole video series.

00:36 And you're going to see how we use this in patient care.

00:40 Let's understand what specific gravity is.

00:42 So let's talk about that first.

00:44 We're talking about a basic elementary definition.

00:48 Specific gravity is a ratio.

00:50 Now, you know when I have a ratio, I'm comparing something to something else.

00:55 With specific gravity, I'm comparing the ratio of the density of a substance compared to a standard.

01:02 Okay, so look at what ratio you have on your screen.

01:05 You've got the density of a substance compared to a standard.

01:10 Now, when we're talking about urine specific gravity, we're going to compare the specific gravity of urine to a standard.

01:18 Look at the pictures I have for you there.

01:21 You see the one has a yellow liquid in it that represents urine.

01:25 The other one is a sample of pure water.

01:29 So just for your knowledge, pure water specific gravity is one.

01:34 So when we compare urine to pure water, remember that ratio involves one for water.

01:41 So how does this help? Well, when you compare the urine specific gravity when you compare that to the density of pure water, which is the standard, it'll show us how concentrated all the chemical particles are in the urine.

01:55 All right, great definition, but what does that really mean? Well, urine is pure water plus stuff.

02:02 Yes, that is the professional term stuff.

02:05 So what we're trying to figure out is how concentrated is that urine? If pure water with nothing else in it is one, everything above one is the extra stuff.

02:18 That's basically what urine specific gravity is.

02:22 Let's look at it graphically, because I do much better when I can see a picture of it.

02:26 So when we do a urine specific gravity test, you need a urine sample.

02:31 And we're going to compare the density of the urine compared to the standard.

02:35 So now we've taken that formula that we showed you in the beginning, and instead of having words, we've put the samples in their place.

02:43 So we're going to compare urine to pure water.

02:48 Now, normally urine specific gravity is 1.010 to 1.030.

02:54 Okay, so I used to say 1.010 to 1.030, just because it's easier for me to remember.

03:02 We know that pure water has a density of 1.00.

03:07 So look at the differences between the two.

03:10 Obviously water is one, but use this time to help yourself start to begin to memorize that urine specific gravity normal values are 1.010 to 1.030.

03:24 Now keeping in mind, we know since we're comparing it to pure water, and we know we're looking for the concentration of the "other stuff" that's in urine, the more concentrated the urine is, the higher the specific gravity will be.

03:39 Now, I know I said that very slowly.

03:43 That's because it's a simple concept but when you're first learning it, it can feel kind of awkward.

03:50 So be patient with yourself.

03:51 Keep in mind, pure water, one.

03:54 So anything with urine is water plus stuff in it, and the higher that number gets, the closer it gets to 0.30 or higher and beyond that, the more concentrated the urine is.

04:09 That means I've either got extra extra stuff in it, or the patient is really dehydrated, and they're not peeing out a lot of water.

04:19 So when the urine specific gravity is high, heading to 1.030 or higher, know that the urine is more concentrated.

04:29 Two ways that it gets there, you got extra stuff in your urine or you have less water.

04:35 Either one is going to give you that ratio.

04:38 So let's walk through how your urine specific gravity is determined, because it's an indication of the kidneys ability to concentrate or dilute urine.

04:48 So we have some hormones in our body that control that ADH is a big one.

04:54 This can be a determinant of how well antidiuretic hormone is working in your patient's body.

05:01 Because the urine specific gravity will let us know how well the kidneys can either concentrate, hang on to water, and only put out stuff, or put out tons of extra fluid which would make dilute urine.

05:14 So adult kidneys are more efficient than immature kidneys of children.

05:18 That kind of goes without saying but keep in mind those urine specific gravity numbers will be a little different.

05:24 Now, I love this picture.

05:27 My friend drew this for us and look at this, a kidney with a pacifier and a diaper on.

05:33 That's to help you keep in mind neonates can have a normal urine specific gravity of 1.003.

05:41 Now, compare that to what you know to be normal for an adult.

05:45 In fact, go ahead and write in the normal value of an adult underneath the baby value.

05:50 Cool. 1.010 to 1.030.

05:54 So, if I get a urine specific gravity back on a neonate, and they're at 1.003, I am not alarmed.

06:01 It's a normal.

06:02 And I hope your brain can use that visual that I have there for you to help you remember that.

06:07 Okay, this is a lot of talk about urine, but I promise if you hang with me, with the repetition that we're using, you're going to have it rock solid by the time we're done with this video series.

06:17 So when you're doing a urine specific gravity test, you need a sample.

06:21 You can either use a dipstick or you can send it down to lab, most often in a clinical setting, We're not going to be doing a urine specific gravity test at the bedside.

06:30 We will send the sample down to lab and they will send the results back to us.