Low Urine Specific Gravity: Causes (Nursing)

by Rhonda Lawes

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    00:00 Alright, on the next slide, I'm going to show you a whole list of things that can cause low urine specific gravity.

    00:07 But I want to give you a framework before I even show you that so you can kind of group them into categories.

    00:14 The first category is endocrine.

    00:16 The second one is glomerulonephritis or pyelonephritis.

    00:20 And the third one is just straight up renal failure.

    00:23 Okay, so keep those categories in mind.

    00:26 If I have a patient whose results come back with low urine specific gravity, these are the categories on our run through my brain, is it an endocrine problem? Is it a problem with glumerulonephritis or pyelonephritis? Inflammation of the kidney? Or is it renal failure? Okay, so here it comes.

    00:44 I've got a long list for you but remember, we've given you those categories to think through.

    00:50 Now, diabetes insipidus that falls in the endocrine category.

    00:54 That means I don't have enough ADH, antidiuretic hormone.

    01:00 So let's use this time to kind of help solidify that concept in your brain.

    01:05 So next to DI or diabetes insipidus.

    01:08 I want you to write a downward arrow and ADH.

    01:11 Just to remind you that that's the opposite of SIADH, which is extra ADH.

    01:17 Now because your body is just dumping off water because it doesn't have the chemical messenger to tell it to hang on to it.

    01:25 Because that's what ADH is job is it's against diuresing.

    01:29 So if I don't have that hormone in my body, I am dumping off all extreme amounts of fluid.

    01:36 That's why my urine will look like water and have a low specific gravity.

    01:40 Now, in kidney failure, the kidneys are not going to be able to concentrate the urine and that's why you also may have a low specific gravity.

    01:49 Now, the next one's just dealing with again, more damage to your kidneys but we're getting real specific.

    01:55 The official diagnosis is acute tubular necrosis that means you have damage to kidneys tubular cells, we just call it acute tubular necrosis, which means death.

    02:06 Definitely qualifies as damage.

    02:09 Pyelonephritis or glomerulonephritis, or inflammation in the kidneys.

    02:13 So that was its own category.

    02:15 But that's a pretty involved diagnosis.

    02:17 So you want to check out our videos that go in depth in these two diagnoses.

    02:23 This one is unusual.

    02:24 You may think you'll never see it, but I have seen it more times than I wish in my career.

    02:30 Psychogenic, means genic is the cause, or the beginning is psyche.

    02:35 That's your brain.

    02:36 So people with certain mental health diagnoses can develop psychogenic, poly meaning many have this extreme thirst that they cannot satiate.

    02:48 They just drink, and drink, and drink, and drink, and drink and I'm not doing it justice.

    02:54 These patients are driven to drink more than their body can handle.

    02:58 Meaning they end up throwing their electrolytes off so much that it becomes life threatening.

    03:02 People have actually died from psychogenic polydipsia.

    03:06 So keep that in mind.

    03:08 The reason their urine has this low specific gravity in the first case was because you didn't have enough endocrine, right? They didn't have enough hormone and diabetes insipidus.

    03:18 The next two items are because the kidneys taken a hit, and it's not really functioning well.

    03:23 So endocrine was the first one, kidney failure, damage to the tubular cells, pyelonephritis, glomerulonephritis those are all damage to the kidney.

    03:32 But psychogenic polydipsia is a case kind of all by itself.

    03:36 The last one is malignant hypertension.

    03:40 Okay, now malignant, that's bad, right? That's real bad when it says malignant.

    03:44 We normally think about that with cancer.

    03:47 But when you put it with hypertension, that means blood pressure that is so high.

    03:53 It's kind of put your life at risk.

    03:55 I have a stroke and I have other experiences but what do we know about the kidneys Remember, we've traced that blood supply.

    04:03 Blood is delivered to the kidneys.

    04:05 When you hit that glomerulus, it's a tingle of capillaries.

    04:08 We know that capillaries are really fragile because things have to go back and forth across those membranes.

    04:14 So it's meant to receive volume at a set rate.

    04:18 If I have malignant hypertension, Boom! those kidneys are getting hammered.

    04:25 So that really can mess with your kidneys.

    04:28 Okay, so how could we rearrange this list of things that we have? Endocrine.

    04:33 Ah, just that one.

    04:35 Diabetes insipidus, When you have kidneys that are taking a hit, which ones fall into that category? Everything else except psychogenic polydipsia.

    04:46 So if I'm looking at a list like this, I'm thinking, can be an endocrine disorder, the kidneys have been taken a hit and there is several reasons how the kidneys can take it.

    04:56 And the very unusual psychogenic polydipsia.

    05:00 There you go.

    05:01 Now you're remembering three things, three categories, instead of six individual items.

    About the Lecture

    The lecture Low Urine Specific Gravity: Causes (Nursing) by Rhonda Lawes is from the course Urine Specific Gravity – Urinalysis (Nursing).

    Author of lecture Low Urine Specific Gravity: Causes (Nursing)

     Rhonda Lawes

    Rhonda Lawes

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