- [Voiceover] Iron deficiency anemia
is anemia due to a deficiency in iron,
and this is a type of microcytic anemia,
but that's something you already know,
because of this diagram in which you saw
that iron is a really important component of heme,
and heme is essentially half of hemoglobin, right?
So that if you don't have iron,
you certainly can't make heme
and without heme, you can't make hemoglobin.
Any time you have a problem with making hemoglobin,
you end up with a microcytic anemia.
A microcytic anemia refers to an anemia
where you end up with really small red blood cells.
So why does that happen?
Is that just something that happened by accident?
Well, no, it's something that the body does intentionally.
So, in any condition where you have a problem
with making hemoglobin, such as with iron deficiency anemia,
you end up with these red blood cells
that have fewer hemoglobin molecules than they should.
So you see something like this,
where you have this big old cell
with very little filling on the inside.
The body responds to this
by cutting this red blood cell in half
so that you end up with smaller red blood cells like this
and each has a small amount of hemoglobin on the inside,
but the point is that the concentration of hemoglobin
inside each of these really small cells
is essentially very close to
what you'd see in a normal cell.
It's almost like if you had a jelly donut
that had very little jelly on the inside
and so the donut shop tried to make up for that
by shrinking the donuts down into munchkins
so that you have these really little munchkins
that were filled plump with jelly on the inside.
Okay?
If you already know all that about iron deficiency anemia,
what is there left to learn?
Well, one of the things we haven't talked about
is the causes of iron deficiency anemia
so we'll talk a little bit about the causes
of iron deficiency anemia.
I like to think of the different causes
as belonging to one of four different groups.
As you can probably tell, I like to think of things
in terms of groups because it helps organize my thinking.
I do very little memorization and more rationalization.
Alright?
So when you usually think of iron deficiency,
you're probably most likely to think of a person
who isn't taking in enough iron through their diet.
You're probably most likely to think of
cause of decreased intake, decreased dietary intake.
We get iron through the diet in foods
like green leafy vegetables and meat,
so certainly somebody who isn't taking enough quantities
of these types of foods will have iron deficiency
but really, decreased intake
is most problematic in little infants.
Little infants.
Especially those infants less than six months old
and that's because when you're younger than six months old
your diet consists almost entirely of breast milk
and breast milk is a really poor source of iron.
That's why infants end up with iron deficiency
and then iron deficiency anemia, alright?
So, another cause of iron deficiency
is an increase in the body's demand.
Increase in the body's demand of iron.
Really, you'll see this in one of two types of patients.
The first type of patient is either
a child or an adolescent.
Adolescent...
The second type of patient you'll see this in
is a pregnant woman.
Pregnant... a pregnant woman.
Okay?
So you know that during childhood and adolescence
we undergo a really rapid rate of growth
and along with that rapid rate of growth,
we experience a rapid expansion in our blood volume,
so our blood volume has to increase as well.
In order to increase the blood volume,
the number of red blood cells has to increase.
You can't increase the number of red blood cells
if you don't increase hemoglobin production.
That increase in hemoglobin production
requires increased iron.
That's what accounts for the increase
in the body's demand of iron
during childhood and adolescence.
You see something very similar going on in pregnant women.
During pregnancy, you can see up to a 20 percent increase
in your blood volume to accommodate
the needs of the growing fetus inside the woman.
That accounts for the increase in the demand,
the body's demand of iron.
It's very easy for these two types of patients
to not take in enough iron through the diet
to meet the increase in the body's demands
and that's how they end up with iron deficiency.
So let's say you have a patient, then,
who's taking in enough iron through the diet
but for some reason or another,
that iron isn't making its way through the gut
and into the body.
What I mean to say is let's say there's a problem
or a decrease in the absorption.
In the absorption of iron.
To understand the different situations
that could lead to a decrease in the absorption of iron,
we'd have to talk about how
the absorption of iron normally occurs.
So, here's a man, okay?
The reason why I put him in here
is to show you that when you take in iron
through the diet, it goes in through the mouth,
through the esophagus, through the stomach
and then to this point.
This point right here called the duodenum.
The duodenum.
Okay?
So the duodenum is a point where you really absorb
almost all of your nutrients, including iron.
Before iron makes its way through the duodenum
and it's absorbed in the duodenum,
it has to go through the stomach,
and it's really important for the iron
to pass through and encounter the stomach
because the stomach contains lots of acid.
That's what I'm drawing in green over here.
Contains lots of stomach...
contains lots of stomach acid.
The stomach acid is essential for converting
the iron that you take in through your diet
into a form that is more easily absorbed
through the duodenum.
It's really important for serving that function.
So, going back to this diagram that we're making over here,
there are really two ways that you could end up
with a problem in the absorption of iron.
The first way is you could just
not be making enough stomach acid,
so you have a decrease in the production of stomach acid.
The second cause, the second way
you could end up with a problem
in the absorption of iron
is having some sort of problem,
some sort of problem in the duodenum.
In the duodenum...
In the duodenum.
So, first let's talk about this decreased acid production.
This really happens very commonly
in two types of patients.
The first is the patient who is taking a drug
called a proton pump inhibitor.
I've abbreviated that PPI, so proton pump inhibitor.
So that's a type of medicine you take
for the treatment of esophageal reflux disease,
acid reflux disease, so that's a disease in which
you have acid refluxing, or going backwards
from the stomach into the esophagus
and it causes irritation of the esophagus,
most commonly referred to as heart burn.
In order to relieve the symptom of the heartburn,
patients will take a drug called a proton pump inhibitor
that decreases the production of this stomach acid.
Now, with decreasing the production of stomach acid,
you get relief in the symptom,
but along with that, you get a reduction
in the absorption of iron through the duodenum.
Okay, so that's one way in which
you could end up with a problem in the absorption of iron.
A second type of patient in which
you'll see a decrease in the production of stomach acid
is a patient who has had a gastrectomy.
A gastrectomy.
A gastrectomy refers to either the partial
or the entire removal of the stomach.
Why would somebody have either part of their stomach
or their entire stomach removed?
Well, there could be a couple of different reasons
why this would occur, but first is
it could be done for weight loss reasons.
To aid in weight loss.
The second reason is it could be done
to remove a stomach cancer,
or even, perhaps, a stomach ulcer.
For whatever reason, the point that we're focusing on
over here is with the removal of part of the stomach,
you have a decrease in the production of stomach acid
which decreases the conversion of iron
into the form that's more easily absorbed by the duodenum
leading to iron deficiency,
and then leading to iron deficiency anemia.
Alright?
So that's the first cause of an impaired absorption of iron.
The second cause occurs with some dysfunction
in the duodenum, or some problem in the duodenum
and really, you see this in patients
who have celiac, celiac disease.
Celiac disease refers to
patients who have an intolerance of gluten.
Gluten is something that's found
in different foods in your diet.
It's found in wheat, barley, rye,
and other types of similar food.
When patients with celiac disease
encounter these, encounter gluten in their diet,
it leads to an inflammation and a destruction
of the cells in the duodenum
so that the duodenum doesn't do as good of a job
absorbing nutrients, including iron.
So that's how patients with celiac disease
end up with iron malabsorption, or a decreased absorption.
So, finally, we have to consider
what I think is the most important cause
of iron deficiency anemia.
So let's say you have a patient
who's taking in enough iron through their diet
and all of that iron is making its way into the body,
but for some reason or another,
they have an increase in the loss of iron from the body,
usually you see this with blood loss, okay?
Because with blood loss, you lose the red blood cells
and then with that comes a loss of the hemoglobin
inside the red blood cells,
and with that comes a loss of the iron
that's inside the hemoglobin, right?
So that's how you end up with iron deficiency.
You see this in a few different cases.
The first especially encountered,
or really only encountered in young women
who have not yet encountered menopause,
is heavy menstrual bleeding.
Heavy menstruation.
Another cause is peptic ulcer disease,
which I've abbreviated PUD.
Peptic ulcer disease refers to
when you have ulcers either in the duodenum
or sometimes in the stomach,
and a lot of times these ulcers can bleed
and with that increase in blood loss,
you can end up with iron deficiency, right?
One of the most important causes
of increased blood loss leading to iron deficiency
is colon cancer, okay?
Most often encountered in elderly patients
and colon polyps.
The reason why this is so important,
aside from the increase of mortality
that you see with this condition,
is because a lot of times this goes unnoticed to the patient
so the patient doesn't notice that
there is blood being lost through the GI tract
in their stool.
It's usually only when an elderly patient
presents with iron deficiency anemia
and you work up that iron deficiency anemia
and try to figure out what the cause of it is
that you discover that he or she
has an underlying colon cancer.
It's something to always keep in the back of your mind,
especially when an older person presents with colon cancer.
Alright, so then let's finally discuss
one of the most common causes of blood loss
in developing countries, and that is
a hookworm infection.
These hookworms can inhabit your intestine
and literally latch themselves on
to the wall of your intestine and suck out blood,
leading to blood loss.
These are the different causes,
lots of the most commonly encountered causes
of iron deficiency anemia.
Keep in mind that iron deficiency
leads to a problem with making hemoglobin
which then, ultimately leads to a microcytic anemia.