00:02
The second major cause of microcytic anaemia
is thalassaemia, the word itself is extraordinary
comes from the Greek the sea and when Greek
soldiers came back after the wars, they look
to the sea thalasses and that is the thing
they said. Thalassaemia gets its name because
it was common in the Mediterranean. It is
due to an imbalance in the production of alpha
or beta globin. You need to make equivalent
amounts of alpha globin or beta-globin make
adult haemoglobin. Alpha-thalassaemia results
from a deficiency of alpha-chains.
00:48
Beta-thalassaemia results from a deficiency of beta-chains and
treatment if required is with a blood transfusion,
which can replace the blood. Now on the right
we have an example of electrophoresis of haemoglobin
and this electrophoresis allows us to identify
different subsets of globin. So if you look
on the left of the normal, you will see haemoglobin
A is dominant. That is alpha-2, beta-2.
01:21
That is the type of haemoglobin in most adults
in the world. Below that is a small amount
of haemoglobin F, alpha with gamma and a small
amount of A2 alpha with delta chains.
01:38
Now if you look next to that, there is a patient
with the beta-thalassemia trait. That means
they are lacking one beta globin genes and
they are still making beta chains, but the
balance between too much alpha and too little
beta is disturbed and you will see that the
A band is reduced. What is interesting there
is you can see that the haemoglobin A2 is
slightly increased. I mentioned that because
that is a very useful diagnostic test.
02:07
If you have somebody, you have small red cells
and you think they may have a beta-thalassaemia
trait, then measure haemoglobin A2 and it
will be slightly increased. Just to the right
of them is somebody with a most severe form
of beta-thalassaemia and you can see that
the A-band now is very thin. There is still
some production of beta globin clearly, but
it is very small. And here when I see more
production of haemoglobin F, which is useful
and can help to provide oxygenation of tissues,
but it is not as effective in an adult as
haemoglobin A. Finally on the right, there
is an example of an alpha-thalassaemia and
this is haemoglobin H disease. It is quite
a severe form of alpha-thalassaemia.
02:57
Still as haemoglobin A so there is some alpha globin
production, but not enough and some of the
beta chains are precipitating out has haemoglobin
H at the top. Noticed that haemoglobin A2
is not increased enough of thalassaemia. So
we do not have an easy test for milder forms
of this disorder. Now if the patient has severe
thalassaemia, they will be chronically and
severely anaemic. The treatment as I mentioned
can be blood transfusions. But if that is
not done to an adequate level, the patient
can be chronically anaemic and that can lead
to massive expansion of haemopoiesis within
the bone marrow. The bone marrow tries to
expand to make more red cells and the characteristic
x-ray although now thankfully very rarely
seen is this the skull x-ray showing 'hair
on end' appearance and that is due to the
expansion of the haemopoietic tissue within
the skull in this patient who has inadequately
transfused thalassaemia. Although transfusions
are effective one of the problems is that
they have a lot of iron in every blood transfusion,
200 mg and so you must remove the iron through
chelation that can be given by deferoxamine
subcutaneous injections or through oral tablets.