So let’s now turn page and say what do
we know about the severity of anemia.
What are the symptoms and
how do we judge those?
Well, the signs and symptoms of anemia
include decreased energy, fatigue,
poor appetite, headaches,
shortness of breath, lethargy
and eventually unconsciousness.
And this is about the order
in which things will present
if anemia is continually
worsening and not checked.
So it will start with a decreased energy
and fatigue and end with unconsciousness.
Likewise, signs and symptoms can get
worse with increasing severity.
So you might start with simply pallor on
the skin, eventually failure to thrive.
You might see a flow murmur
or hear a flow murmur.
A patient might begin getting orthostatic
and then they’ll be baseline tachycardic.
They may, if their tachycardia is
unchecked, develop hypotension,
and resulting in a need for
intervention for their breathing
and that can eventually
lead to unresponsiveness.
So there are certain historical
clues in patients with anemia
that might lead you
quickly to a diagnosis.
And I want to go through
these key historical clues because
there are things you should ask when you
see a patient who you suspect has anemia.
In a patient who is 8-12 weeks
of age, we expect anemia.
Because this is called
the physiologic nadir.
A baby is born with fetal hemoglobin.
They rapidly lose their fetal hemoglobin
and have to replace it
with adult hemoglobin.
Keep in mind, the half-life of
the fetal hemoglobin is shorter
than a half-life of
and that the lifetime of a cell is
about 80 days instead of 120 days.
As a result, the patient
around 8-12 weeks of age
starts losing that fetal hemoglobin and
then the adult hemoglobin starts rising up.
And that leads a little dip point
when children this age typically
have low hemoglobins,
around 9, 10, 11.
Patients who have pica may
have iron deficiency.
Pica before the anemia may
be a behavior phenomenon
and maybe this child has lead poisoning
from having eaten lead in the environment.
A really common one we see all the time
is children who are fed too much milk.
These children will get iron deficiency by
virtually being on a cow’s milk only diet
because the iron is cow’s milk is less
bioavailable and there is less of it.
Patients on a goat’s milk diet
will have folate deficiency.
Patients with weight loss,
maybe they don’t have a nutritional
deficiency, although they might.
May be they have a systemic illness
that is driving that weight loss.
For instance, a patient with Crohn’s
disease may have antecedent weight loss
for a few months beforehand and
present with a normocytic anemia
because of general dysplastic or
rather suppression of the bone marrow
that’s happening inside the bone
marrow from just being inflamed.
Additionally, of course, we’re going
to ask about lead environment
in any patient when we’re
worried about anemia
because of the prevalence of lead
poisoning in the United States.
So when we see a patient with anemia,
we think in these boxes of
increased destruction and decreased
production and active bleeding,
but when we get the labs back,
we don’t get that information.
What we get back from the
lab is the MCV and the RDW.
In any patient with an anemia,
you must check both the MCV and the RDW
because these are going to help
you categorized the anemia
and they are very valuable cues
as to what’s causing the problem.
I’m going to go through this carefully.
In microcytic anemia, which
is an MCV of less than 70,
the leading causes are iron
deficiency and lead poisoning.
These 2 things you must know.
be on the test.
In a patient with a normocytic anemia,
this could be acute blood loss or this
could be anemia of chronic disease.
Patients who have general inflammation
who aren’t making red
blood cells very often,
but the red blood cells they
can make are generally normal.
Likewise, in patients with large red
blood cells with an MCV over 85,
they are more likely to have
a B12 or folate deficiency.
Those are incredibly important and
highly likely to be on your test.
So let’s understand the RDW because I
think it can be confusing to some people.
Here are two individuals.
This is a histogram of the
size of their red blood cells.
You can see that on average, the green
person has slightly lower hemoglobin,
but there is a narrow distribution of
the sizes of those red blood cells.
On the contrary, the person with the
red line has a higher hemoglobin,
but there is a larger population
of both small and large cells.
So the hemoglobin is right here.
This is the MCV.
This is the average size
of those red blood cells
and you can see the person
with the graph in red
has a slightly larger population of cells
than the person with a graph in the green,
but there is a lot of overlap.
To assess how wide those
curves are, we use the RDW.
So the person in the
red has very high RDW
and the person in the green
has very narrow RDW.
This is a very unique situation.
This is a patient who has both iron
deficiency which makes small red blood cells
and folate deficiency which
makes big red blood cells.
If you saw this patient, you
would say their MCV is normal.
It’s right down the middle,
but clearly this is not a distribution
and so you would see a really huge RDW.
That would be your clue that
something is going wrong.
What about the reticulocyte count?
So the reticulocytes are
baby red blood cells.
They are just few steps
before the erythrocyte.
So a low reticulocyte count implies
that the cells aren’t being made.
An example would be very recent and
rapid destruction or blood loss.
If I acutely bleed out, it will
obviously take a week or so
before I’m starting to be
able to make reticulocytes.
It could also mean, however,
a decreased production.
If there are fewer cells coming down the
pike, there will be fewer reticulocytes.
A high reticulocyte count
implies that the bone
marrow is doing its best
to replace your loss.
So if I have a chronic indolent
autoimmune hemolytic anemia
where I’m constantly breaking down my red
blood cells in a pretty reasonable rate,
I may have a high reticulocyte count
because I am trying very
hard to overcome that loss
or for example, a slow progressive
loss like a chronic GI bleed.