Let’s take a look at our second
enzyme deficiency when dealing with
normocytic hemolytic anemias and
this is pyruvate kinase deficiency.
How is it that you have a glycolytic
enzyme, one that’s deficient,
that may result in an
Listen to what I just said.
There’s an enzyme deficiency that’s
going to then render the RBC
to be destroyed by the spleen.
What is this about?
Well, let’s take a look.
glycolytic pathway is what
you are referring to.
At the very bottom portion here,
you’ll find that phosphoenolpyruvate
has to be converted into pyruvate.
That’s where this
enzyme is missing.
but the boards love this question because
of its integration of many other subjects
as you shall see and you know that I get so
elated when we have such points to make.
Once again, there’s your
enzyme pyruvate kinase,
normally responsible for converting
phosphoenolpyruvate to pyruvate.
if this enzyme is deficient,
it’s an intrinsic disease because
it’s a problem within the RBC,
but the way that the RBC is now misshapen,
which we haven’t talked
about yet, but we will.
It will be then taken to the
spleen for destruction.
So why does the boards
love asking this so much?
Because if you’re moving
down the glycolytic pathway,
you’re trying to feed the pyruvate
to your TCA or Krebs cycle,
you can’t even create the pyruvate.
So therefore, it goes back to that age old
concept of what then happens
to the substrate proximal
to the enzyme
deficiency or block.
It always increases.
So now, not only are you going to have
increase in phosphoenolpyruvate,
but you’re going to back up, back
up, back up, into your 2,3-BPG.
The increase of your 2,3-BPG or
bisphospho or dibisphosphoglycerate,
what is then going to do your
oxygen dissociation curve?
Pathologically, it is then going
to increase or facilitate
the release of oxygen
from your hemoglobin.
So this then means a right
shift, are we clear?
Point number one as to why
the boards love asking this.
We’re not quite done
yet, we’ll see more.