00:01
Alright,
we've looked at the physical
appearance of the urine.
00:04
We look at the pH of the urine.
00:06
Now let's spend some
time in specific gravity.
00:09
Now, I can learn about the
patient's hydration status
and their kidneys ability
to concentrate urine
from this number.
00:16
The specific gravity
of pure water is 1,
and I know that urine is water
with other things
dissolved in it.
00:24
So it makes logical sense
that the urine specific gravity
should be greater than 1.
00:28
In fact normal is 1.010-1.030,
still with me?
Good deal, okay now,
I'm not trying to confuse you
but I'm going to show
another value on the screen.
00:41
But before I do,
I want you to keep in mind
that's the value I recommend
for you to memorize for NCLEX.
00:47
Okay,
that's a good reference range.
00:50
I'm putting this one up
here just to let you know
that some labs might consider
1.002 to 1.030 as normal.
00:59
I put it up there just as a
caveat for you to be aware of
but if I was memorizing
for the NCLEX,
it's 1.010 to 1.030,
that's the value
I would go with.
01:11
Now have you ever wondered why there
aren't units with specific gravity.
01:15
It's kind of weird, isn't it?
It's because specific gravity
of urine is just a ratio.
01:21
We're looking
comparing one substance
to another substance.
01:25
In the case of urine
specific gravity,
we're comparing urine to water,
so that's why we don't
need any type of units.
01:33
Now a specific
gravity and hydration.
01:37
The greater a
number is past 0.10
you're moving towards
relative dehydration.
01:45
Okay. So at 0.1010,
no, I'm not dehydrated.
01:50
But I want you to have the
concept put your finger on 1.010,
now move it towards 1.020,
move it towards to 1.030,
as you're going that direction
in the numbers are going up.
02:05
It's moving you
towards dehydration
because the higher the
specific gravity number is
that indicates the
severity of dehydration.
02:15
Now again, it's not that 1.24
is dehydrated and 1.22 isn't
it's all on a spectrum and
what your patient can tolerate.
02:25
But know that urine in the 1.010
range is going to be be lighter
much lighter than
urine at 1.030.
02:36
So the higher the
specific gravity number is
it indicates the severity
of the dehydration.
02:41
Now what are underlying causes
of higher specific gravity?
Dehydration.
02:46
We just talked about it.
02:47
What is glycolysuria?
Will uria means urine,
glyco means sugar.
02:54
So if I have extra
glucose in the urine,
that means I've got
more things dissolved
in that water in the urine,
and that's why my urine specific
gravity would be higher.
03:06
Remember pure water is 1,
the more things I have
dissolved in my urine
the higher the number of
urine specific gravity.
03:14
Now glucose in urine
or diabetes mellitus,
you're going to end
up with extra things
in your urine and a
higher specific gravity.
03:23
Same principle applies
to proteinuria.
03:25
Someone might have
nephrotic syndrome
their kidneys are struggling
they end up with
protein in their urine
that's going to be more
things dissolved in the urine
and a higher specific
gravity number.
03:38
Remember protein is supposed to
stay in your blood not in your pee.
03:43
So if we have protein being
dumped into your urine,
that's a sign that the
kidneys are struggling.
03:49
Shock we've got issues with
your kidneys being perfused.
03:53
And so they're not able to
really release a lot of water
because they're trying
to hang on to everything
as a compensatory mechanism
to raise your blood pressure.
04:02
Last one is SIADH.
04:04
That's an endocrine imbalance,
where you have excess
of this hormone,
anti diuretic hormone.
04:12
If I have excess ADH,
then on a hanging
on to everything
and I'm not putting out
very much water at all
with my urine and that's why my urine
specific gravity will be higher.
04:24
Okay now what if it's lower,
everything's just
the opposite right?
So the closer I am to 1.010,
that's means I'm
relatively hydrated
because the lower the
specific gravity number is
that means the
concentration of urine
is not as intense as it is
moving towards 1.030.
04:46
Okay,
so give me your finger again
if I was at 1.030 put your
finger there where that would be
and as you're moving
along the continuum,
you should be at about 1.020 now
know that your urine is
becoming more dilute.
05:03
This patient is probably
becoming more hydrated
if they were dehydrated.
05:07
So 1.020 keep on
moving to 1.010.
05:13
I'm still within a lot normal
range, normal range,
but I want you to have in
mind the lower that number is,
there's less things
dissolved in that urine
so it's becoming closer and
closer and closer to pure water
with nothing dissolved in it.
05:31
Now what am I thinking about
if I get a urine analysis back
on a patient and I see a
low urine specific gravity.
05:37
I want to look at
the following things.
05:39
First of all,
are they on any diuretics?
Okay, because that's going
to cause them to dump off
all kinds of excess fluid.
05:46
Is it possible?
They could have
diabetes insipidus.
05:50
Do they have adrenal
insufficiency.
05:53
Okay now we are really messing
with the endocrine system.
05:57
Diabetes insipidus remember
that is not enough ADH
or I can't respond
to the ADH I have.
06:04
Adrenal insufficiency.
06:06
Okay so you adrenal glands
sit on top my kidneys, right?
Those are those little
endocrine organs.
06:11
I have an Adrenal medulla
and I have an adrenal cortex.
06:15
Now, the cortex comes
all those corticosteroids
but out of the medulla I've
got like epinephrine pen
all those things,
all those hormones
that come out of
my adrenal gland.
06:27
But it also has aldosterone.
06:30
Now aldosterone is a hormone
that tells my body
to hang onto sodium
and wherever sodium
goes what follows?
You got it,
water!
Okay so, whoa, that's a lot of
stuff about the endocrine system.
06:45
We got diabetes insipidus because
we've talked about that before.
06:48
Adrenal insufficiency.
06:50
One of the things my adrenal
glands, squirts out is aldosterone.
06:55
So that's that same
thing from the RAAS.
06:59
So when my body recognizes,
hello I do not
have enough volume.
07:04
It responds by squirting out,
aldosterone.
07:08
When the aldosterone
cames out my kidney say,
whoa, hang on to sodium
when my kidneys hang onto sodium
then it naturally they
hang on the water.
07:19
If my adrenal gland
is insufficient,
I don't have the
ability to do that.
07:24
So what do I do?
I'm not getting the
message to hang onto sodium
and I saw water just
keeps leaving my body
instead of being reabsorbed
like I need it to be
the floodgates have opened.
07:37
So that's why specific gravity
of urine in adrenal
insufficiency will be low.
07:44
What will their urine look like?
Pale,
very pale.
07:48
It's going to look like water.
07:50
Because instead of
hanging under water,
your body is just letting
it leave your body
because it doesn't have
the hormone messenger
to tell it to hang on to it.
07:59
Okay, that's a lot of stuff.
08:00
So let's back up a little
bit, diuretic
Yeah, that's working in
the parts of my kidney
tell my body to put
out extra water.
08:08
Diabetes insipidus,
I don't have the chemical
messenger that tells me
hang onto water.
08:13
Adrenal insufficiency
that's going to be
another endocrine problem
because I don't get the message
to hang on to sodium and water,
so it's all leaving my body.
08:24
Now let's look at
the other side.
08:26
If you have aldosterone and
impaired renal function.
08:28
We've got that same
issue with aldosterone
and you could have early stages
of chronic kidney disease.
08:36
Okay catching a clue here.
08:38
Yeah, all of this either
impacts the kidney on some way
or as a direct problem
with the kidney.
08:46
So I'm either giving
you a medication.
08:48
You have an endocrine disorder
or your starting to see the early
signs of chronic kidney disease.
08:54
Those are all possible reasons
of a low urine specific gravity.
08:59
Now,
how do I know which one it is?
Well, you can't tell from
the urine specific gravity.
09:04
Remember that's your job.
09:05
Anytime a lab value is abnormal,
that's a warning
shot to you to know,
hey, I got to dig deeper into
the patient's assessments
and their history and their meds
and figure out why this is low.
09:18
Now,
this is the saddest one of all
fixed urine specific gravity
means it doesn't change.
09:24
So that urine specific
gravity will stay the same
right around 1.010,
which is normal,
but it doesn't matter how much
fluid the patient takes in
or doesn't take in.
09:36
It's essentially unchanged.
09:38
I like to say that means your kidney
is the equivalent of a pet rock,
fluid is going through it,
but it's not changing it
in any way shape or form.
09:47
This can often
happen after chronic
glomerular nephritis, remember that's
inflammation in the glomerulus.
09:54
So this is a really
really bad sign.
09:57
If you have fixed
urine specific gravity,
you need multiple urine
analysis to identify that
and you clearly
do other testing,
but if you have
a patient who has
an intrinsic renal
insufficiency,
they've had chronic
glomerular nephritis,
you would expect that as it
progresses and gets worse,
you'll see fixed urine
specific gravity.
10:18
So it'll hang out right
there about 1.010,
no matter what you do
as far as fluid volume.