High Urine Specific Gravity: Other Causes (Nursing)

by Rhonda Lawes, PhD, RN

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    00:00 Now let's look at some other possible causes of high specific gravity.

    00:04 First of all, the most obvious one is volume loss.

    00:07 How do I lose volume? I can be really dehydrated, I can have diarrhea, vomiting, fever will cause fluid to just think of it as evaporating.

    00:17 It's your body's attempt to try to cool that body down.

    00:20 There's even some medications that can cause a high specific gravity.

    00:24 Sometimes of a patient's in congestive heart failure, because the urine that's coming out of their body is really scant, or a small amount.

    00:32 Now, wait a minute, that doesn't make sense.

    00:35 If somebody has congestive heart failure, they have all this extra fluid on board, right? That's what we call heart failure.

    00:43 Right.

    00:44 They have all this extra fluid on board, but because that heart is floppy and mushy, and it can't pump effectively, then what's not getting perfused? Mm hmm.

    00:55 The kidneys, right.

    00:56 Those are the guys that take a hit first.

    00:59 So because the heart is not able to push blood throughout the body effectively, the kidneys are not getting perfused.

    01:06 Kidneys that aren't being perfused put out smaller, and smaller amounts of urine.

    01:12 The urine they do put out is going to be pretty dehydrated and yucky.

    01:16 Now what about renal artery stenosis? That's another issue with the kidneys.

    01:20 they're not getting good blood flow, right? We've got those arteries that are smaller due to stenosis, closing in a yuck in those arteries.

    01:29 That's why you're going to have a high specific gravity because those kidneys are not being perfused.

    01:35 Okay, so the first one was we don't just have enough volume circulating around.

    01:39 Congestive heart failure, oh, we've got the volume.

    01:42 We just don't have the pump that can move it around.

    01:46 Now, in renal artery stenosis, you may have the right volume on board, but it can't be delivered to the kidneys because those vessels have been compromised.

    01:54 Now, Shock! Yeah, that one's a problem.

    01:57 I hope that got your attention.

    01:59 because the issue of shock it's kind of like what we see in congestive heart failure.

    02:04 I don't care how you got the shock, right.

    02:07 What it means is there's not enough oxygen being delivered to the cells to meet the body's metabolic needs.

    02:14 So whether it's anaphylactic shock, hypovolemic shock, you name it, septic shock, whatever it is, those kidneys aren't getting perfused.

    02:24 So, number one, volume loss.

    02:27 We don't have enough going around.

    02:28 Kidneys aren't being perfused.

    02:30 Number two, congestive heart failure.

    02:32 Pump is not working. Kidneys aren't getting perfused.

    02:35 Renal artery stenosis, not good delivery of blood to the kidneys.

    02:40 Kidneys aren't getting perfused well.

    02:42 Shock.

    02:43 Hey, you picking up a theme here? Yeah, that whole left side of the column.

    02:48 You unlikely to have a high specific gravity when the kidneys are not being perfused well.

    02:53 So do you need to memorize a paragraph? No.

    02:56 Just know that when kidneys are not perfused well they can't be put out a lot and that's why you're going to have a high specific gravity.

    03:05 Now, we're getting fun.

    03:05 Look at SIADH.

    03:07 You know how I love to say Hormone.

    03:10 I just like it to help me remember.

    03:12 So I'll be walking through the mall.

    03:14 and I'll hear somebody say from five years ago, "Hey, Prof. Lawes! Hormone!" Which may not play well in the community, but it does make me laugh when I run into old students.

    03:23 So SIADH is an endocrine disorder.

    03:26 You got too much. It's inappropriate.

    03:29 You have too much ADH.

    03:31 Now look at that word.

    03:33 This is going to help you in other contents.

    03:35 So anti means against.

    03:38 So anti, just write in against.

    03:41 Diuretic, well you know what that means.

    03:44 That's like lasix or furosemide.

    03:46 That makes you pee out everything.

    03:48 Hormone is just a messenger.

    03:51 So antidiuretic hormone means I'm against diuresing.

    03:59 Okay, that's the message that's delivered.

    04:02 So if I'm against diuresing, am I peeing out a lot? No.

    04:08 I'm against diuresing.

    04:09 Mine, mine.

    04:11 I'm going to hang on to all that water.

    04:13 So the urine and I put out is going to be dark and yucky.

    04:18 That's why it's gonna have a high specific gravity.

    04:21 Urine specific gravity is comparing the urine to water.

    04:25 Water is 1.0 because it's pure and nothing's dissolved in it.

    04:28 What they're putting out is just stuff dissolved essentially in a very tiny bit of water.

    04:34 That's why the specific gravity will be high.

    04:38 So when you're taking care of your endocrine patients, or you're taking a test, remember you don't have to memorize the specific gravity of a patient with SIADH. Think it through.

    04:48 Know that they're against diuresing that means they hang on to a bunch of water what they put out is dark, and dehydrated.

    04:57 Last one, trauma, stress reactions, surgery, and some drugs can also cause an ADH secretion.

    05:06 So anybody that has some extra ADH, even if it isn't SIADH could also end up having high specific gravity.

    05:15 What's the number one thing I'm going to remember? Hey, when those kidneys don't get perfused well, what they put out is going to be dark and highly concentrated.

    05:23 That's the most important takeaway point.

    05:26 Then I'm going to fill in SIADH and the other ones, but the most important point you could probably pull out is when you see a change in your patient's urine.

    05:36 When it looks darker, you'd be thinking that urine specific gravity is likely high.

    05:42 Now, some other causes of high urine specific gravity.

    05:45 These aren't the common ones.

    05:47 We've talked about dehydration, that's the most common.

    05:50 But if I've got somebody whose glucose goes up, their urine specific gravity goes up.

    05:55 Whoa, whoa, whoa, whoa, whoa, whoa.

    05:56 Okay, before we start talking about four more things that you have to remember, I want to walk you through that.

    06:04 Okay, so if I have extra glucose in my urine - no, that's probably not a good thing.

    06:09 You're right.

    06:10 That's not a good thing.

    06:11 But why does my urine specific gravity go up? Ah, that's easy. We know.

    06:15 Think back to our picture.

    06:17 We know that urine specific gravity is comparing urine to pure water.

    06:22 Pure water doesn't have anything dissolved in it.

    06:24 Urine does.

    06:26 So if I have my urine with the normal mineral and compounds in it, plus extra glucose, I've got extra stuff.

    06:34 That's why my specific gravity is higher.

    06:39 So that's another thing you want to start looking at.

    06:41 If a patient has high urine specific gravity, what's that glucose looking at? What about protein? Oh man, we know protein urine is a bad sign.

    06:51 Remember, that's a sign that kidneys are really struggling.

    06:55 Those nephrons are damaged.

    06:57 Protein is supposed to stay in your blood.

    07:00 Okay, so protein supposed to stay in your blood that helps us keep fluid in our intravascular space.

    07:06 If too much of it is getting out into our urine, and if you've got enough protein in your urine to raise your high specific gravity, that's definitely an issue.

    07:16 Now, urine specific gravity won't tell us how high the protein is, we'll have to do another test.

    07:21 What about red or white cells? Again, it's just more stuff in the urine.

    07:27 How would I know there's red cells? Well, if it's visible, there's a clue.

    07:31 You might be able to see it.

    07:32 But you can't always see those in the urine.

    07:35 What about white cells? Yeah, the urines gonna look kind of cloudy and yucky.

    07:40 So you might be able to visually see that or you may not.

    07:44 And last, bacteria.

    07:46 That's why we look at the color and clarity of urine.

    07:50 If it's got bacteria in it, it's gonna have sometimes a real fun odor, and it's going to look cloudy.

    07:57 So we talked about the main causes of high specific gravity, it's when the kidneys are not being perfused well.

    08:03 We also laid in there, SIADH.

    08:06 And now these other four things.

    08:07 So just group this category as extra stuff dissolved in it, what am I concerned about? Sugar, protein, red or white cells, or bacteria.

    08:19 So these are things that you're going to need to stop before urine specific gravity testing if you want an accurate one, because these drugs can cause an increase in urine specific gravity.

    08:29 So that doesn't mean, - nope, I'm not going to give that volume expander because I'm going to test the urine specific gravity.

    08:35 You just want to keep in mind that if urine specific gravity is off, and they're on dextran, that's likely the cause.

    08:42 So just want to keep an eye on the trends.

    08:45 Now, dextran is a plasma volume expander and they make it from sugar, which is why I have pictures of little sugar cubes over there.

    08:53 But things like dextran, sucrose, or a contrast diet is given IV can cause an elevated urine specific gravity.

    09:03 Here's why.

    09:04 The dextran is a plasma volume expander but when the body is getting rid of those products, it's going to show up in the urine.

    09:13 And that's why the number is going to look high.

    09:14 Once the dextrans runs through your system, it shouldn't impact the urine specific gravity anymore.

    09:20 Sucrose, same thing.

    09:21 If we put you on that, intermittently, you're going to see that elevated, but once the sucrose is worked through, you're good to go.

    09:29 Last one, IV contrast dye.

    09:31 Well, that means I'm shooting something in your vein, because I want to look very closely at something in your body.

    09:37 I want to take pictures of it.

    09:39 It's with that dye moves through your body you'll see a temporary elevation in the urine specific gravity.

    About the Lecture

    The lecture High Urine Specific Gravity: Other Causes (Nursing) by Rhonda Lawes, PhD, RN is from the course Urine Specific Gravity – Urinalysis (Nursing).

    Included Quiz Questions

    1. The kidneys do not get perfused
    2. The majority of the fluid is in the lungs
    3. The fluid is in the interstitial tissues and not in serum
    4. The body is severely dehydrated
    1. Multiple bouts of vomiting and diarrhea
    2. Atherosclerosis of the renal artery
    3. Increased secretion of antidiuretic hormone (ADH)
    4. Excessive fluid intake
    5. Decreased secretion of antidiuretic hormone (ADH)
    1. Glucose 345 mg/dL
    2. Sodium 137 mEq/L
    3. Potassium 3.5 mg/dL
    4. Albumin 4 g/dL
    1. Bacteria
    2. Protein
    3. Red and white blood cells
    4. Sodium
    5. Urea
    1. Contrast dye
    2. Sucrose
    3. Dextran
    4. Normal saline
    5. Magnesium

    Author of lecture High Urine Specific Gravity: Other Causes (Nursing)

     Rhonda Lawes, PhD, RN

    Rhonda Lawes, PhD, RN

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