In this lecture, we’ll
So rhabdomyolysis is caused essentially
by massive muscle cell destruction.
This massive muscle
results in a release of intracellular
contents into the blood,
so that in turn causes myoglobin to go into
the blood and then it is often peed out.
And it’s the urination that
can cause problems.
So what causes a massive
muscle cell breakdown?
Well, there is traumatic causes such
as a crush injury or immobilization.
Additionally, patients may have
rhabdomyolysis from exertion.
This is particular likely among
patients with sickle cell trait
or patients with myopathies.
Additionally, patients may
just be weekend warriors.
They are hanging out a lot during the day,
during the week they are not working much,
and on the weekend they decided to do
some very hardcore physical activity
which causes muscle breakdown.
Extreme exercise can do this.
We sometimes see this, for
example, in marathon runners.
And prolonged seizure can also cause
an exertional rhabdomyolysis.
Lastly, there are some other
common causes of rhabdo.
One for example is influenza.
We are not really sure
why, but the flu virus
can often cause
significant muscle pain
and rarely that can in turn
result in rhabdomyolysis.
Patients with myositis or inflammation
of the muscle can certainly get rhabdo.
Also occasionally drugs of abuse especially
stimulants can cause a rhabdomyolysis.
Lithium can do it and
also malaria can do it.
Snake venoms can rarely
cause a rhabdomyolysis
and in particular, pit vipers.
Also hypokalemia in of itself can cause
muscle breakdown and a rhabdomyolysis.
So how do patients
Well, they are having muscle
breakdown and that tends to hurt.
So these patients do
tend to have myalgias.
Also they will note that their urine
color has turned dark red or brown.
This is the myoglobin
coming out in the urine.
These symptoms are usually consistent
with an underlying problem.
So if a patient has, for example,
they should have symptoms
of dermatomyositis as well.
Generally, we worry about rhabdomyolysis
if the CPK or creatinine
phosphokinase is over 10,000.
Those patients may be at
risk for renal damage.
We are not really confident
about that 10,000 mark,
but it seems like a reasonable place
to draw the line in the sand and say,
"Now we should worry about
this patient’s kidneys."
Rarely, in very severe rhabdomyolysis,
patients may have a high
potassium or a high phosphate
as a result of release of
those intracellular contents.
If there is renal involvement, patients
will have a high BUN and creatinine.
What I mean to say is, with very high levels
of CPK, usually around 50,000 or greater,
patients can end up in renal failure
and that’s what we worry
about in this condition.
Urinalysis will, of course, show myoglobin
if you’re worried about a
patient with rhabdomyolysis.
So how do we manage rhabdomyolysis?
The key thing is
aggressive IV hydration.
We want to give IV hydration
at very high rates
so that we’re keeping
the urine dilute.
That prevents the renal
damage from the myoglobin.
So we’re going to give sometimes as
much as 2 times maintenance IV fluids,
so that we can get that CPK down low and
the patient will gradually get better.
Previously, you may have read somewhere
about the alkalinization of the urine.
We used to believe that by adding
bicarbonate to the IV fluids,
you may reduce renal damage.
It turns out this isn’t
really in fact really effective.
So nobody's really doing this anymore,
but you might see that in older texts.
What’s key about rhabdomyolysis
is managing the hyperkalemia
or other electrolyte
Usually if it’s severe,
it’s usually not necessary.
For renal injury, we’re
going to follow creatinine
and in very severe cases,
dialysis may be required.
So that’s my review, very
briefly, of rhabdomyolysis.
Thanks for your attention.