Lecture 12 & 13 - Urolithiasis Flashcards
what factors influence precipitation?
- solute
- proteins, inhibitors
- surfaces present
- bacteria
- pH
- other ions
what do stones likely result from?
nucleation + growth + aggregation from crystals
all aided by retention of urine
is finding crystals in urine significant?
not necessarily. it just indicates urine is supersaturated which indicates a risk for urolith formation
when are uroliths significant? if you see signs of….
- secondary bacterial infection
- obstruction
- hematuria, pyuria (pus in urine)
- urgency, stranguria, pollakiuria
how do you diagnose uroliths?
imaging - contrast studies, endoscopy
what are some treatment options for uroliths?
- emergency tx
- medical tx
- catheter removal
- urohydropropulsion
- cytoscopic retrieval
- lithotripsy
- surgery
describe emergency tx of uroliths. what is most impt?
tx hyperK and acidosis is most impt!
place IV catheter and start fluids then deal with the obstruction
describe medical tx of uroliths. what is the overall goal?
the goal is dissolution of the urolith. this is accomplished usually thru the diet.
need to know stone type in order to do the following with the diet:
- reduce solute
- modify urine pH
- alter population of ions
what tx is used for “sand” sediment?
catheter removal - flush, refill and repeat technique
describe urohydropropulsion
fill bladder under anesthesia and express to achieve a forceful stream and collect for examination
what is lithotripsy and what are the 2 kinds performed?
lithotripsy is when you have a fragment stone in vivo but the procedure is not much different from just performing surgery
- ESWL: shock waves outside body used when uroliths are stuck in one location like ureteroliths or kidney stones
- intracorporeal (laser) lithotripsy: laser up to stone, usually done for cystic calculi
which tx is most commonly performed for uroliths?
surgery is most common - usually a cystotomy
when should preventative strategies be considered?
- recurrent urolithiasis
- nephro or ureterolithiasis
- no underlying cause
- underlying cause that cant be controlled
what is a non-specific prevention?
increasing water consumption! it decreases the amount of mineral in urine and this is super impt!!
what are the most common stone types?
- struvites
- urates (purines)
- compound uroliths
what are struvites and how are they usually treated?
they are the most common
- dogs with struvites will also have UTIs, cats will not
- will often respond to dissolution and pH modulation
what type of acidifer should you use with struvites?
ammonium chloride for pH modulation
when do you need the alter a diet long-term for a patient with struvites?
dogs with sterile struvites and cats
do you need to give abx to patients with struvites?
dogs should receive abx bc struvites are usually associated with a UTI in dogs.
treat like a complicated UTI - this means they need abx for 3 - 4 months!!
Calcium Oxalates - how are they treated? what are the risk factors for getting them?
Ca oxalates cannot be dissolved, they must be physically removed.
- 30 - 50% recur in 3 years
risk factors:
- breed = yorkies, mini-schnauzers, Lhasa, shih tzu
- obesity
- glucocorticoids
- primary hyperparathyroidism
- chronic metabolic acidosis
hydrochlorothiazide
- decrease ca excretion
- effect blunted with increased water consumption
potassium citrate: what are its 2 actions and when should you consider using it?
- pH modulation - urine alkalinizer
- corrects hypocitraturia - decreases available ca in the urine
consider using when: diet and thiazides have failed and to achieve target pH
does vitamin supplementation help prevent uroliths? Vit B6? Vit C? Vit D?
nope!
B6 - no data
C - avoid, can increase oxalates
D - avoid, potential for increase Ca
purines - how are they treated?
check to make sure liver function is ok!
- diet/pH modulation - decrease protein in diet and aim for a neutral to slightly alkaline pH
- allopurinol - xanthine oxidase inhibitor. not recommended for prevention unless diets and alkalinization fail. not good for animals in liver failure.
cystine: when do they occur? how are they treated?
- uncommon
- M»>F
- characterized by cystinuria
- frequently recurrent
Tx: decrease protein in diet and pH modulation
what is the process of urolith formation? how does it start?
it starts by having urine be supersaturated.
precipitation –> nucleation –> cystallization aggregation
