00:01
Hello and welcome to the
Nephrology curriculum.
00:04
Today we're going to be talking
about chronic kidney disease.
00:07
And if you're taking
care of patients,
you will definitely encounter patients
who have chronic kidney disease.
00:11
So it's important
to understand it.
00:15
Let's start out with
a clinical case.
00:17
A 29 year old woman,
is noted to have
microscopic hematuria
with two plus
positive-dipstick proteinuria.
00:24
And remember, of course no
proteinuria on the dipstick is normal.
00:28
And this is taken
on screening labs
for a life insurance policy.
00:32
It was confirmed on a
repeat urine analysis
three months later at her
primary care doctors office.
00:37
Her serum creatinine
however as normal.
00:41
Now let's go to another
case of a 52-year old man
with a history of hypertension
who is noted to have
a serum creatinine
at 1.7 milligrams per deciliter
and we can see by the normal
values that that's elevated.
00:53
His urine analysis
however is unremarkable.
00:56
In review of his past records,
His serum creatinine
was also elevated to 1.7
milligrams per deciliter
about six months prior.
01:04
So the question is
which one of these patients
has chronic kidney disease.
01:10
Let's go through
the history and see
if we have some clues
to our diagnosis.
01:14
So in our first case
of a woman who's going for
her life insurance policy,
she has a history of microscopic
hematuria and proteinuria
and it sustained over time
because when she reject her
Labs at three months time,
she also had hematuria.
01:29
So that's really suggestive
of chronic kidney disease
in terms of that there's
clinical damage to the kidney.
01:36
How about our second
case of our gentleman
who has an elevated creatinine.
01:40
A high creatinine means
that his GFR or glomerular
filtration rate is lower.
01:45
And again,
this has been sustained over
a three-month period of time.
01:49
So this gentleman has chronic
kidney disease as well.
01:53
So the answer
is that they both actually
have chronic kidney disease.
01:58
So how exactly do we define
chronic kidney disease?
It's really based on
either having kidney damage
or decrease in GFR over time.
02:06
Let's focus a little bit more
closely on kidney damage.
02:09
What does that mean exactly?
It could be that there's a
pathologic abnormality of the kidney
meaning that if my patient
perhaps is diagnosed
with IGA nephropathy.
02:18
I have a renal biopsy.
02:19
I look at that biopsy and I see
evidence of clinical disease
with IGA nephropathy.
02:24
Even though their
creatinine is normal.
02:26
Let's say it's 0.7.
02:28
They still have evidence
of disease by biopsy.
02:32
It could be clinical
markers of kidney damage.
02:34
That would be something
like proteinuria.
02:36
So normally we excrete less
than a hundred fifty milligrams
of protein in her urine
when it exceeds that greater
than a hundred fifty milligrams
and that sustained over time,
that would also be a marker
of having kidney damage.
02:50
Albumin which is which is
the principal component
of protein in the urine
if that is greater
than 30 milligrams
that also exceeds the threshold
of having normal values
so that patient will also have
evidence of clinical damage
if that sustained over time.
03:06
Glomerular hematuria is another
sign of clinical damage.
03:10
That means that you have those
funny shaped red blood cells,
we call them dysmorphic
because they have funny
shapes on their membrane
as they have bloods,
blebs since they transverse that
glomerular basement membrane.
03:21
We can also see things
like red blood cell casts
when we see that clinically,
we know that that patient
likely has glomerular damage.
03:31
Other clinical markers of
kidney damage include Imaging
so I might have a patient who
has polycystic kidney disease
and they potentially could
be early in their course.
03:40
So again could have a
normal serum creatinine,
but when I image them with
something like an ultrasound
I might see multiple cysts
which would indicate that
that patient also has
chronic kidney disease.
03:51
I might be seeing something like
hydronephrosis on ultrasound.
03:55
So this is an ultrasound
that shows a kidney
that has hydronephrosis
essentially that's
urine that's backing up
into that renal pelvis
So you see that big
dilated renal pelvis
that big boggy cortex
if that sustained over time
that is also a clinical
marker of kidney damage,
and finally,
here's an ultrasound
that shows a kidney
that's very echogenic
meaning that it's
brighter than the liver
on ultrasound
and you can see that the
cortex is quite thin.
04:21
When that happens,
that's also a marker of
chronic kidney disease
despite the fact that the serum
creatinine might be normal.
04:27
So it's important to
keep that in mind.
04:30
Now we also talked
about another way to
mark kidney damage is a
decrease in kidney function
that would also
signify that that patient
has chronic kidney disease,
and I think that's what most
of us traditionally think about
when we have a patient with
chronic kidney disease.
04:45
That means that the GFR or
glomerular filtration rate
is less than 60 mils per
minute per body surface area
for greater than
3 months duration.
04:56
So just keeping in
mind a normal GFR
for most people is somewhere
between 90 and 120 mils per minute.
05:04
Now this decrease in GFR of
less than 60 mils per minute
really needs to be
sustained over time
meaning that we have to have
at least two measurements
separated at least two weeks
in addition to that
greater than 3 months
of decrement and function.
05:18
We want to make sure
that that's real.