Now, let's look at some of these other ones.
MCV means mean corpuscular volume.
That's the average volume
of the red blood cell.
This is really what I want you to look at.
Just know what MCV is, that it's
the mean corpuscular volume,
and that's what it tells us -- the average
volume of the red blood cells.
I've put the formula up there for you,
but don't memorize that.
That's not worth the real
estate in your brain,
but that is how it's calculated.
You take the hematocrit, divide
it by the red blood cells,
and that will give you the average
volume of the red blood cells.
So we know that the mean
corpuscular volume tells us
the average volume of the red blood cells.
So, when is this elevated? When
do we end up in macrocytosis?
Well, if you have reticulocytes. If they
increase, we have reticulocytosis.
Now, reticulocytes are bigger
than mature blood cells.
They might have a B12 or
a folate deficiency.
They might be taking methotrexate
for maybe rheumatoid arthritis,
or they're on phenytoin, which
we give for seizures.
So you can end up in macrocytosis
with certain medications,
nutritional deficiencies, or reticulocytes.
Now we have microcytosis. They're decreased
when a patient has iron deficiency.
Okay. In case your eyes have glazed over,
this is one of the ways that we can figure
out what's the cause of a patient's anemia.
If their MCV is too low, we could consider
iron deficiency or thalassemia,
or anemia from a chronic disease, hemolytic
anemia, or even lead poisoning.
Now I know that seems like
a pretty bizarre list.
Just keep in mind, MCV is a
mean corpuscular volume.
If it's too low, then know you
need to dig deeper
and look at the possible reasons
that could cause that.
MCH means mean corpuscular hemoglobin.
Now this is another calculated value.
We get it from the measurement of
the hemoglobin and the red blood cell.
We have the formula for you
there so you know how it's figured,
but we want you to focus on MCH
is the average amount of hemoglobin
contained within each of the red blood cells.
If we've got low MCH, we've got some examples
that could have come from a
blood loss, or an iron deficiency,
lead poisoning shows up again,
or anemia of chronic disease.
If it's high, if we have a higher value,
might be macrocytic anemia,
the red blood cells might be just too
big, and that can happen with alcoholism,
liver disease, low levels of
B12, or folic acid.
So, the next time you have a patient
that you know has had
a long history of alcoholism
and they've got a CBC drawn, just take
a look at the MCH and see what it is.
It'll be an indication that they have either
a history of alcoholism or liver disease.
If that lines up with their history,
you'll start to really understand
why these values can tell us
so much about your patient.
Okay. The mean corpuscular
Do you understand why we call it MCHC?
That's the hemoglobin times
100 divided by the hematocrit.
And it just tells us the average concentration
of hemoglobin in a red blood cell.
So MCHC is used to help diagnose the type,
cause, and severity of an anemia.
So whether it's iron deficiency, lead
poisoning, or anemia of a chronic disease,
we would expect a low MCHC.
If it's high, we're going to really
start looking at an autoimmune
or an idiopathic hemolytic anemia.
You'll also see this in
your sickle cell kids,
or someone who's had a severe burn.