Finally, there's cystine stones or cystinuria.
This is an autosomal disorder.
It's a tubular defect in dibasic amino acid transport resulting
in increased cystine, ornithine, lysine and arginine excretion.
Stones typically don't start forming
until the 2nd or 3rd decade however,
that can manifest also as a staghorn
calculi or multiple bilateral stones.
Treatment for cystine stones are really gonna be
directed at decreasing urinary cystine concentration.
So a low sodium diet is actually helpful
but it's not exactly clear how that works,
it's not exactly the same mechanism
as it is in calcium-based stones.
Increasing the urinary pH
greater than 7.5 would be helpful
but that's oftentimes hard to do for a
patient to take that much alkaline material.
Medications like tiopronine and penicillamine
are also helpful as they bind to cystine.
The side effects really limit their use.
Okay, what about your urological interventions? When
do we need to have our Urology colleagues involved?
We definitely want to get our colleagues involved for immediate
intervention if our patient is coming in with urosepsis,
that means they've got a stone
in association with infection.
if our patients have acute kidney injury
particularly because of the obstructive uropathy,
if our patients are anuric -
they're not making any urine,
or if they have ongoing pain that's
recalcitrant to any type of therapy.
We need immediate intervention
from our urology colleagues
Outpatient intervention, we can wait on
these if our patients potentially have stones
greater than 10 milimetres in diameter and fail
the pass them with conservative management.
That would be an indication to
refer your patient to a urologist.
In here what they can do is
extracorporeal shock wave lithotripsy.
They can do ureteral lithotripsy that means
they're actually endoscopically entering that ureter
and they're breaking that stone up.
They can do a percutaneous nephrolithotomy
and that's what I showed before in that image
where they're the actually making
a tract directly into that renal pelvis.
And lastly, they can do a laparoscopic stone removal.