This is a table here. It is a nice table to
summarize the things that we have talked about.
Let me dissect this for you. In general, this
is all about creatinine clearance. First and
foremost, we will talk about two ends of the
spectrum. We will talk about increased creatinine
clearance and common causes for that and possibly
why and then as we complete the high yield
or most common cause of increased creatinine
clearance, we will then go into what is known
as decreased creatinine clearance. Let us
begin. So normal pregnancy. Close your eyes.
Think about a pregnant lady. Next, what might
you be thinking about? Her plasma volume.
As soon as she becomes pregnant in general,
what about her plasma volume? It increases.
Does it not? So in a normal pregnant woman
with an increase in plasma volume, I am now
delivering increased amounts of plasma to
my afferent arteriole thus to my glomerulus.
What Starling force are you now increasing?
Good. Hydrostatic pressure. Excellant. Which pressure
is that? The pulling or the pushing pressure.
So you have increased the amount of plasma
volume arriving at the afferent arteriole
in the glomerulus, it is going to push more
substances or in other words filter more.
So now if you filter more with a normal kidney,
what will you then expect at the end of the
first trimester when usually the plasma volume
might increase as much as 50 percent. Obviously
an increase in creatinine clearance. From
physiology, a concept that you must keep in
mind also dealing with pregnancy important
for renal function is something called renal
threshold for glucose and we will spend some
time with that and all that I wish to say
about this at this point so at least I plan
to seed in your head and then we will further discuss
this as how the renal threshold for glucose
decreases in a pregnant woman? Fact, the renal
threshold for glucose decreases in a pregnant
woman. There is more glucose in the urine
of a pregnant lady on purpose. In general,
when you have a pregnant lady, what is her
plasma glucose? It will be elevated in general
because you want to feed the little bit of
baby. The fetus is hungry. So it will be fun
when we get to that point. Move on. So now
that is a normal pregnancy. Let us talk about
diabetic early on and with diabetes,
there is going to be two major issues within
the renal region and here it would be the
blood vessels that are affected much more
so with efferent interesting enough. So now
think about where you are and don't just read.
Conceptualize the efferent arteriole. Where
are you? Distal to the glomerulus. Correct
and if it is diabetes, what kind of blood
vessel change do you find in general? Tell
me about diabetes mellitus. Is that a chronic
issue? Is that an acute issue? It is a chronic
issue. 10, 15, 20 years have taken place.
You may or may not have controlled your glycemic
control maybe you didn't monitor properly.
Really difficult at times. You think about
HbA1c and all these things and so, therefore,
the type of pathology that takes place with
diabetes mellitus is called non-enzymatic
glycosylation or you might notice it as being
advanced glycosylated end products for the
most part similar and more importantly is
that the blood vessels are undergoing a process.
Please highlight in your head. Hyaline arteriolosclerosis.
How important is that? Very. Hyaline, what
does that mean? Accumulation of protein. Now
the enzymatic glycosylation might then contribute
to this hyaline, which is what color? H&E stain
eosinophilic and it will be pinkish and this is
accumulating in the lumen of the
blood vessel causing what? Constriction okay
great not so much for the patient, but the
concept is great. Isn't it? So you are going
to constrict, constrict and constrict pathologically
the efferent arteriole. Are you picturing
this? So what may then happen proximally?
You added a resistor in a series, what then
happens proximally? An increase in pressure.
When increase in pressure, then what happens to
hydrostatic pressure? It increases. Let me ask
you something. You want to discipline your
child. You discipline your child and maybe
you lose respect or whatever, but then you
spank. What if you continue spanking, spanking,
spanking, spanking? My goodness at some point
you are going to damage the buttocks of that
baby with enough spanking. Well with efferent arteriole
constriction you are spanking the glomerulus.
Spank, spank, spank, spank and so, therefore,
are you now perhaps causing damage. Yes, you
are and what is the first thing that you will
be looking for in dipstick in a patient that
you suspect diabetic nephropathy. It is called
microalbuminuria. You should never have albumin
in your urine. So when the time is right and
we talked about dipsticks, we will talk about
the microalbuminuria and say that now the
glomerulus is damaged apart from the protein
that might be passing through is it possible
that you might have increased creatinine clearance?
Absolutely. That is my topic. You see as to
how you are going to use this information
but then also clinical application in terms
of overall what is happening. May I ask you
one other thing that you may or may not have
thought of. As soon as you have microalbuminuria,
what kind of drug that you might you want
to give your patient. It is called a renal
protective drug or an ACE inhibitor and I
will introduce that here. At some point, we
will reinforce that and you will have seen
that in pharmacology and that is an important
drug so that you can protect the efferent
arteriole in the glomerulus from further kidney
damage. Let us continue, please.
Increased GFR, damage of glomerulus, hyperfiltration
injury is what you are looking at as being
part of early diabetic nephropathy. So if
this is increased creatinine clearance, then
let us take a look at decreased creatinine
clearance. Elderly people, as we get older
what we will say beyond the age of 50, there
is a drop in GFR one milliliter per minute.
So, therefore, elderly people will have an
automatic increase in creatinine clearance
and why is that important to you. We just
discussed earlier as to how it is important
that you measure or assess kidney function
by using the clearance formula UV/P. Once
you do so, you will get renal function assessment
and you want to make sure that you understand
an adjust the dose of your nephrotoxic drug.
Acute and chronic renal disease once again
now with acute renal disease or acute renal
failure, we will talk about different phases
as you will see. Acute renal failure is going
to be a completely different manifestation
than chronic and that is important as a distinguishing
point and I wish to point out here and I will
keep repeating it until it becomes firmly
etched in your head, but there are times with
acute and definitely chronic in which because
you can’t filter properly. What then may
happen to creatinine clearance? Well here
if you can’t filter properly, you will then
be decreasing creatinine clearance. So what
does that mean? That means less has been cleared
there is more that ends up being wear in your
plasma. Let us continue.