In this lecture, we’re going to discuss
clotting disorders in children.
Let’s pause for a moment and
re-remember Virchow’s triad.
This is the setting in which clots
can form inside blood vessels.
This happens as a result of blood stasis,
through endothelial damage and
because of hypercoagulable state.
And in this lecture, we’re
going to focus a little
bit on the hypercoagulable
state of children.
In general, clots in children
are far rarer than in adults.
Their endothelial lining
is in perfect condition,
but they may have a hypercoagulable state
that can lead them to form blood clots.
So let’s talk about the primary
causes of hypercoagulability
and the first one I want to talk
about is factor V Leiden mutation.
Factor V Leiden mutation is a mutation
that causes resistance in the
breakdown of factors by protein C.
So this is the most common inheritable
cause of hypercoagulability
and it presents typically in adulthood,
not in childhood, but rarely can.
This is usually presenting with
arterial and venous clots in patients.
So another one is
antithrombin III deficiency.
This is a problem where antithrombin III
forms a complex with activated thrombin,
factors 10A, 9A, and 11A.
Antithrombin III neutralizes
these clotting factors
patients die in utero,
but heterozygous patients
often have venous thrombosis.
And they usually present in the teen years.
Another type of hypercoagulability
is protein C and S deficiency.
If you recall, protein C
and S are necessary for
breaking down clotting
factors VA and VIIIA.
Patients who are heterozygous
for this condition
may present with mild
increased risk for clots
generally in their
second decade of life.
However, homozygous patients
will present in infancy,
specifically in the neonatal period with an
entity called neonatal purpura fulminans.
This is obviously an
incredibly rare condition,
but these patients have clots
all over through their body
and mortality is quite high.
Let’s talk about prothrombin mutations.
That’s another primary cause
In patients with prothrombin mutation,
this can result in excess
thrombin and formation of clots.
There is an increased risk in adulthood,
it’s less commonly found in children.
Lastly, the MTHFR mutation.
The MTHFR mutation is a genetic cause
of increased homocysteine in the blood.
Basically, it’s a mutation in
This enzyme is responsible for turning
homocysteine into methionine.
And because it’s not working so well,
these patients have a higher
level of homocysteine.
This results in a blood vessel wall damage
and resultingly, a hypercoagulable state.