Let's talk about that bleeding time.
Now, before we take a look at that, bleeding time.
What is my actual time?
2 to 7 minutes.
What is bleeding time measuring?
Let me give you three options.
Is it measuring the activity of your platelet?
Is it measuring the activity of your
Intrinsic or extrinsic?
It's only measuring the activity of your platelet.
There are two reasons as to why the bleeding time
could be elevated,
meaning to say above 7 minutes.
One could be, the platelet itself
wasn't properly aggregating or adhering,
or number two, the platelet wasn't
present, we call that thrombocytopenia.
Let's take a look at aspirin.
What does aspirin do?
Remember, NSAIDS and aspirin inhibits COX.
In the COX pathway of the
arachidonic acid pathway,
what was the component responsible
for platelet aggregation, remind me?
Thromboxane, TXA2, thromboxane.
Renal failure may then cause
platelet aggregation defect.
When it does, you'll have an increase
in bleeding time, look for that.
Please do not confuse renal failure
with nephrotic syndrome, okay?
In nephrotic syndrome, you may lose in maybe about
5 to 10 percent of your patient's antithrombin III.
If you lose antithrombin III, your patient
is in the state of hypercoagulation.
Fascinating, isn't it?
Whereas if it's renal failure, like I said, we
don't know exactly what the signaling is yet
but we definitely know that the
platelets are not functioning properly.
And then, for whatever reason
that cause thrombocytopenia.
For example, you've heard of
immune thrombocytopenic purpura?
You've heard of thrombotic
thrombocytopenic purpura, ITP, TTP
or even in DIC, disseminated
Those are conditions in which your
platelet count is going to drop, no doubt.
Those are the conditions in which you
would find an elevated bleeding time.
Now, be careful here, Von Willebrand disease,
now, the type that I am only going to focus upon
is the type of Von Willebrand Disease where the
patient is deficient of Von Willebrand factor.
Now, our topic for this
discussion is only bleeding time.
So therefore, Von Willebrand factor,
if it's not present, now you remind me,
the fact that we have an elevated bleeding time,
is that due to, not binding to glycoprotein 1b,
or is it due to the fact that
factor VIII will not be stabilized?
It's the prior, isn't it?
So when you don't have the Von Willebrand
factor binding to glycoprotein 1b,
you can expect the bleeding time to be elevated.