- [Voiceover] Hey guys, this is Dr. Joel coming at you
with Part Three of Three in the Complete Blood Count series.
If you started on this video you might want to back up
and watch Part One first.
You can click on this link here to do that.
Or if you have seen that video you can click
on this link to see Part Two.
In the current video, this is Part Three,
I'm going to be covering the platelets,
and then I'm going to talk about the MPV,
or the mean platelet volume.
Then I'm going to talk about the CBC fishbone,
which is a shorthand method to write out a CBC,
you're definitely going to need to know that
on your wards or your clinical rotations.
And then I'll give two Knowledge Challenge questions,
or CBC examples that we can work through and talk about.
All right? Let's get started!
This is the entire CBC that I started with
and so far in Parts One and Two I've talked about
the white section and then the red section,
the white blood cells and the red blood cells,
and as promised in this lecture we are going
to jump right into the platelets.
Platelets are also referred to as thrombocytes,
which is important later on when we talk about
thrombocytosis or thrombocytopenia.
They have a diameter about 2-3nm,
and to help you get a kind of visual reference
of how large this, I'm going to add a backdrop of a red blood cell.
Red blood cells have a diameter of about 8nm or so.
It's a good ruler if you're looking at a microscope slide
to just say a red blood cell is 8nm
and then to judge other cells by that size
so you can see that they are considerably
smaller than red blood cells.
Platelets are produced from megakaryocytes,
which are large bone marrow cells with a lobulated nuclei.
Platelets, of course, are anuclear;
they don't have a nucleus.
They're formed from these megakaryocytes
by just kind of budding off or being produced as
blebs from the cell membrane of these megakaryocytes.
The exact process is still being worked on
but it's enough to know that they bud off
in such a fashion.
Platelets as we know contribute to hemostasis,
or our body's ability to stop bleeding.
They work with the Coagulation Cascade to form
a platelet plug and they do this in three stages.
First, they adhere to the endothelium that has been damaged.
Then, they activate themselves and the picture
on the right shows inactivated platelets on the top
and activated platelets on the bottom.
You can see that the activated platelets just look stickier,
and that's because of the dendrites, or little fingers,
that they have coming out of them that help them
stick together and form that platelet plug.
And then lastly they aggregate,
which means that more and more platelets come to the rescue
and they clump together and begin to form that plug.
So now having talked about what they are
and a little bit about what they do,
what do you think might be the cause for Thrombocytosis,
which is another way of saying of an increased number
or and increased count of platelets in the blood?
And for real quick side note,
I don't have time to talk about these upcoming
diseases in this lecuture.
If you want to learn more about those,
you can click on the links and then learn about them directly.
In this lecture, again, we're just talking about the CBC.
How about acute blood loss?
Our body can sense acute blood loss and to react that
we can release more stored thrombocytes from the spleen,
which acts as a kind of reservoir or a temporary storage.
Chronic Myelogenous Leukemia is another one.
Iron defeciency can actually cause a thrombocytosis.
Polycythemia vera and Hyposplenism is saying,
is another way of saying either you're missing a speen
or your spleen is working improperly.
Now next on to thrombocytopenia.
What do you think causes thrombocytopenia?
Idiopathic thrombocytopenic purpura,
try saying that 10 times fast!
There's a couple of different dieseases that
kind of fall in to that class.
Next, what about HELLP syndrome?
Which is related in pathology to preeclampsia.
Hemolytic-uremic syndrome and also
Disseminated Intravascular Coagulation or DIC.
Alright now into the MPV,
which stands for the Mean platelet volume,
and that's just almost exactly what it sounds like.
It is the calculated measurement of the platelet size.
Now, one kind of cheat that you can use is that
platelets size often increases with an increased production,
and vice versa.
They'll often decrease with a decreased production.
Again, it's not always the case but it's just something
that might help you if you get stuck.
We use the MPV to help us figure out or to diagnose
different causes of changes to the platelet production,
and it help us get a good differential in our diagnosis.
So first off, what could cause an increase in MPV?
How about immune thrombocytopenic purpura?
Or some of the myeloproliferative diseases?
Bernard- Soulier syndrome and pre-eclampsia?
As for the decrease in the MPV,
you may see that with aplastic anemia
or some drugs that are toxic to the bone marrow cells,
so Cytotoxic drugs,
and also in some certain viral infections.
You could see that.
And now that I've forced you to listen to all that,
for a moment of honesty, pure honesty, with you,
I really don't look at the MPV very much.
It's just not something that you'd look at in general practice.
If you get into hematology you might start looking at it,
but for general practice it's not really used that often.
At least that has been my experience.
Now let's talk about a little bit of shorthand.
This is actually really common
and I would say that it is pretty much standardized
when you write out the shorthand for a CBC.
This is how it's going to look.
You're going to have the hemoglobin and the hematocrit
in the center with the white blood cell count on the left
and the platelets on the right.
I use this. All my residents, all my attendings use it.
Everyone that I have met uses this fishbone for the CBC.
It's not the only fishbone however,
there are other fishbones or shorthands.
For example, here's a couple of other ones.
On the bottom left, you can see the basic metabolic profile
shorthand and this is also standard.
I have never met anybody who doesn't use this shorthand.
In the top middle, this is for the calcium mag phosphate.
I have seen this written in different ways
so it is not as standardized and the same goes
with the coagulation studies in the upper right.
The PT, PTT, and INR studies, they write those
a little bit differently depending on where you're from.
Then in the bottom right is the ABG shorthand
and that is pretty standard.
I haven't seen anyone write that differently.
If you want to learn more about those other studies there,
you can click on those links and go check those out as well.
But pretty high yield if you are going into a clinic,
to at least know the left two shorthands for the CBC
and the BMP or the basic metabolic profile.
All right guys congratulations you've made it to the
1st Knowledge Challenge in the CBC series of videos,
and if you have gotten this far after
watching all three CBC videos...
Wow good for you!
I would have started watching Monster Truck videos
a long time ago so... you go!
So let's see what do we have here?
Well, let's say that someone brings this to you
and conversationally they want to know what you're thinking.
So this is the fishbone, this is the shorthand for the CBC,
and I don't expect you to know 100%
where everything is right away
and that's why I'm going to give you a cheat
in the upper lefthand corner.
So we can see that the white blood cell count
is at 12 and 1/2, and the hemoglobin is at 14.9,
the hematocrit at 46.2 and the platelets at 270.
What the heck does that mean? What's normal?
Well again I'm going to help you out.
I'm going to put normal underneath the values.
So, what do you see?
Well, the white blood cell count is too high.
It's above normal. The hemoglobin is in normal range.
The hematocrit is in normal range
and the platelets are in normal range.
So right away you know something is wrong with
the white blood cells. They're too high.
Usually this means there is an infection.
Now, if you clinically know the patient and know the history
you can probably guess what kind of infection.
However, if you had no clue what was going on
you might wanna see the entire CBC just to see
a breakdown of the white blood cells to give you
a better idea of what kind of infection
this patient might be fighting.
So here it is.
Here's that same CBC except printed out completely.
Again, white blood cells are too high.
What else is too high? Well the neutrophils.
The neutrophils are too high.
If you remember back from the first lecture,
we talked about neutrophils being high
for things like an acute infection.
What kind of an infection, you ask?
Well, is it going to be a parasitic infection?
Is it going to be a viral infection?
How about bacterial?
You're probably going to see a high neutrophil count
in an acute bacterial infection.
For a parasitic infection,
you will probably expect the eosinophils to increase,
and for viral infections lymphocytes maybe some monocytes,
those would increase.
Then the basophils might increase with
an allergic reaction of some kind.
Next up! Knowledge Challenge #2.
See if you can figure this one out without using the cheats.
Cheat #1 and Cheat #2.
So what do we got?
We know that the white blood cells are in normal range.
So that is probably not an infection of any kind.
However, the hemoglobin and the hematocrit are too low.
So this is an anemic patient.
The platelets are also a little bit high,
it's normal range but a little bit high.
So that's something to think about.
What do you think is going on?
Well, again, if you knew the patient's history,
if you knew a little bit about the patient,
you might be able to make a guess what kind of anemia
you're looking at.
However if you have no idea,
you're going to want the entire lab slip.
So here it is. Here is the entire lab slip.
Go right to the red blood cell section or the red section
and I'll be honest with you,
the work up of an anemia based on lab values
is a lecture in and of itself because there are
several different causes of anemia
and it's kind of tricky to work through when you're first learning.
A little bit of practice and you'll be an old pro at it.
Let me give you a couple pointers here.
Let's look at the MCV.
The MCV is telling us that
the Mean corpuscular volume is a little bit low
and the same with the Mean corpuscular hemoglobin.
So the body is having a hard time making red blood cells.
It's not just that you bled out
and you have a decreased hemoglobin
because you have an acute bleed.
In fact, at the source in the bone marrow
you're body is having a hard time making hemoglobin.
Alright, so that gives you a little bit of a clue.
This is in fact is an example of iron deficiency anemia,
and I can only really know that
if I did further iron studies,
but if I didn't do the other iron studies,
what else could it be? This is a microcytic anemia.
Well, it could be one of thalassemias
or maybe an anemia of chronic inflammation
or sideroblastic anemia.
Again, working up anemia is little more complex
than just getting a CBC but I think you get the idea.
This is an anemic patient and the problem is
in production not blood loss.
I'm going to put a link up here at the top.
Where you can go see a lecture that is just
devoted to figuring out the anemias.
If you've got time you can check that out.
So good job on this 2nd Knowledge Challenge.
Hey thanks for sticking around guys.
I hope you like this lecture.
If you did, please give me a like.
The likes keep me motivated.
I need to feel the energy to keep on going.
Like I said, I got a day job.
I'm a resident so this is my extra time here.
Subsribe? I'm putting out new videos as fast as I can,
and lastly give me a comment,
let me know what you think,
and I do my best to get back to everybody, alright?
Thanks guys! Good luck in school.