Hello, in this lecture, I'd like to introduce you to the
range of diseases that can be seen within the blood system.
The outcomes that we'll get from this lecture are
quite wide ranging.
You'll see that there are many types of disorder
that can arise from the blood system
and the good way to approach these is to break
them down into three different areas:
red cells, white cells and disorders of blood clotting
which will include platelets and the coagulation factors.
We'll see that red cell problems are dominated by
anaemia, for which there are many causes.
The most important disorders related to white cells are
leukaemia and lymphoma and I'll introduce those to you.
Finally, platelet disorders and coagulation problems
and very different patterns of bleeding
and we'll discuss the major causes
of these disorders.
Let's start with red cells.
On the right there you'll see a very beautiful
picture of the red cells.
Now if there is a reduction in the number of red cells
or the haemoglobin concentration in the blood,
this is called ANAEMIA. This is a very common disorder
and the body becomes deprived of oxygen because
of course the major function of red cells is
to carry oxygen to the tissues.
So the sort of clinical problems that the patient
develops are tiredness, shortness of breath,
perhaps problems in concentration.
Now anaemia may arise because of a decrease in
the production of red cells or an increase
in the destruction or loss of these cells.
Let me try and classify that for you in another way.
So here you'll see a diagram showing decreased
production of red cells and how that may occur.
And at the top in dark green, you'll see 3 categories
and in the middle, reduced bone marrow erythroid activity
due to problems with general bone marrow function,
aplastic anaemia or leukaemia.
On the right, you'll see ineffective red cell formation
due to disorders such as inflammation
and on the other side, you'll see nutritional
deficiencies: iron, vitamin B12 deficiency
and you'll see that all of those feed down into a
failure of production of the red cells by the bone marrow
On the left of the bottom line, you will see two causes of
loss or destruction of red cells - bleeding
or increased destruction through hemolysis.
And finally on the right hand side, an unusual
cause of anaemia, which is where it's just apparent
because of dilution of the red cells by
an increased plasma volume.
Let's look at this in a little more detail,
particularly on the decreased production of red cells.
As a key factor here to remember,you may get a
decreased production of red cells because of a complete
bone marrow failure. Now, in that case, all the blood
cells in the blood will be reduced, the white cells
and the platelets, so its normally quite apparent.
All the reduction in red cell production can be specific,
just the red cells and that can be due to factors
such as nutritional deficiency of iron and vitamins
which are needed for hemopoiesis. It can occur through
inherited disorders of haemoglobin or due to chronic
diseases or kidney problems.
We will discuss these in a little more detail.
Now one useful approach for trying to sort out these
different sorts of anaemias is the size of the red cell.
You will see along the top there in blue. The anaemia
type can be classified into those three groups:
(1) microcytic and hypochromic disorders. What does
that mean? Microcytic - small red cells,
hypochromic - a reduction in the amount of haemoglobin.
So they don't stain as well on the blood film.
That's one major classification. If we follow that line
down, you will see that the red cell indices show
that the MCV and the MCH - that means the mean cell
volume and the mean cell haemoglobin are both low.
You'll see at the bottom, iron deficiency and thalassaemia
as the causes. I'll address that in a minute.
In the middle section, (2) normocytic, normochromic-
normal size, normal amount of haemoglobin.
You'll see there that the red cells indices are normal
and at the bottom, a range of possible causes:
blood loss, hemolysis, chronic disease or marrow
And on final section, (3) macrocytic disorders.
You will see here the MCV and MCH were actually increased.
These are big red cells carrying more haemoglobin,
and the major cause is a megaloblastic anaemia.
Let's look at that in a little more detail.
Microcytic red cells are seen in two major disorders.
That's the key point to remember, two major diagnoses,
of which iron deficiency is the more common.
Thalassaemia is the other major disorder and that's
an imbalance in the production of the globin chains -
alpha and beta.
Normocytic red cells, normal sized red cells observed in
disorders of the bone marrow, inflammatory diseases
or where the kidney is not functioning properly,renal
disorders and that is due to a reduction in
Finally, large red cells, macrocytic red cells
are a feature of vitamin deficiencies particularly
vitamin B12 and folic acid.
I shall also mention hemolysis here, hemolytic disorders
where red cells are being destroyed. They are normally
normocytic but they can be occasionally macrocytic
because young red cells- reticulocytes are slightly
larger than red cells and they may just push the MCV up
just a little into the macrocytic range.
Now the opposite of anaemia is polycythaemia.
That's when you have too many red cells in your blood.
This can cause problem because the blood gets very thick,
very viscous and it gets quite hard for the heart to
pump this thick blood around the body and they can also
increase the risk of thrombosis, blood clotting.
That's quite a serious concern.
Now polycythaemia can be a natural response of the body
trying to adapt to hypoxia - reduction in oxygen tension
and this can occur quite commonly in people who
smoke heavily, who have lung problems or indeed live
perhaps at high altitude.
Now here we see the body trying to respond to
this hypoxia by increasing erythropoietin (EPO)
If we took a blood test from these patients,we would
see that the erythropoietin level is high.
This can also occur in patients who develop a clonal
expansion of red cell precursors in the bone marrow
called Polycythaemia Vera and here erythropoietin
level is normal or reduced.
The bone marrow is essentially out of control.
It's not responding to erythropoietin.
It is growing autonomously, on its own producing
too many red cells.
You will see on the right-hand side a slide I wonder if
you can associate this with polycythaemia.
If you notice carefully the patient here has nails
which are just slightly blue, cyanotic as we call it,
the patient is hypoxic. You may also notice that the
patient's nails are clubbed and they're very rounded.
This is a patient who had a long standing heart defect
leading to cyanotic problems with the blood and that
can lead to very thick blood, very high haemoglobins
because of increased levels of erythropoietin.