Low Urine Specific Gravity: Causes (Nursing)

by Rhonda Lawes, PhD, RN

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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 glomerulonephritis 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, PhD, RN is from the course Urine Specific Gravity – Urinalysis (Nursing).

    Included Quiz Questions

    1. Decreased secretion of antidiuretic hormone (ADH)
    2. Inflammation in the kidneys
    3. Extreme thirst
    4. Hypotension
    5. Urinary tract infection
    1. Psychological disorder that results in extreme thirst
    2. Psychological disorder that results in overeating
    3. Physiological disorder that results in extreme thirst
    4. Physiological disorder that results in overeating

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

     Rhonda Lawes, PhD, RN

    Rhonda Lawes, PhD, RN

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