Let’s talk further about SIADH.
History and physical for sure; findings, here
Euvolemic patient, what does that mean?
What’s eu- mean, the prefix?
It means normal.
You’ve heard of euthyroid, here we have
Serum sodium levels and plasma osmolarity,
What about urine osmolarity?
Low BUN, serum uric acid, everything is being
diluted, diluted, diluted.
Now, at the very bottom of this, it’s important,
SIADH cannot be diagnosed without excluding
hypothyroidism and adrenal insufficiency.
Once again, keep in mind that whenever you
are dealing with ADH, other endocrine dysfunctions,
especially thyroid and the adrenals, are important
for you to make sure that you rule out.
What do you want to do?
Always come to the underlying cause.
If your issue was a lung cancer, completely
different steps of management.
If your patient was on drugs, which is carbamezapine,
obviously remove the offending agent.
Whatever it may be, you want to keep things
in mind, pulmonary disease and treatment,
cessation of drugs, hormonal replacement and
adrenal insufficiency or even perhaps hypothyroidism.
These are things that you are paying attention
to when dealing with SIADH.
Restrict free water intake.
Here, once again, caution must be exercised
with patients with SIADH secondary to subarachnoid
haemorrhage due to exacerbation of the vasospasms
and infarction from the drop in blood pressure.
Keep that in mind.
So, if your patient, extremely important clinical
point, is the fact that if there is going
to be head trauma and it’s due to subarachnoid
haemorrhage, be very, very careful because
if there is going to be ADH and vasospasm,
it only makes matters worst up in the brain.
That’s a huge clinical point that you can
use for every single board that is ever presented
Restrict your free water intake please with
If a patient becomes symptomatically hyponatremic,
hypertonic saline can be given to correct sodium levels.
However, the only thing that you want to worry
is the fact with any time you’re giving
IV saline, whatever the indication may be,
dehydration, maybe SIADH, so and so forth,
is that you never give it rapidly because
if doing so then you’re always worried about
an interesting side effect, but nonetheless,
incredibly significant called central pontine
SIADH pharmacologically… high salt in conjunction
with loop diuretic.
Remember, you are trying to get rid of this.
Now, is all the loop diuretic going to be
Well, it all depends, but sodium is going
to be incredibly important.
Vasopressin receptor antagonists is what you’re
thinking about here.
Because there’s too much SIADH, we’ll
talk about these in a second, and you have
a particular V2 receptor blocker known as
conivaptan and this is then given as IV only,
V2 receptor blocker.
Pharmacologically speaking, with vaptan as
being a V2 receptor blocker, we have an oral
analog known as tolvaptan and interesting
enough, you have demeclocycline and lithium.
Stop here for one second.
The boards will ask you the following.
Here’s a-Here’s a patient that requires
demeclocycline, here is a patient that is
bipolar taking lithium.
This, ladies and gentlemen, will bring about
nephrogenic diabetes insipidus that we do
Now, your patient has SIADH and the patient
with SIADH where there’s too much V2 receptor
activity, wouldn’t you want to then induce
nephrogenic diabetes insipidus?
And that’s the thinking that you must have
here when dealing with demeclocycline and
Antagonize ADH in action and can be used in
a rare patient who cannot be treated with
vaptan the drugs mentioned above.
Steps of management… restrict free water
Get rid of that fluid if you’re thinking
about loop diuretic, but once again keep in
mind of the sodium levels.
V2 receptor blockers and these are your vaptan
drugs: conivaptan, IV, tolvaptan, your PO
If these are refractory, then you start thinking
about drugs such as demeclocycline and lithium.