Lecture 12 & 13 - Urolithiasis

Question 1

what factors influence precipitation?

Answer 1

1. solute
2. proteins, inhibitors
3. surfaces present
4. bacteria
5. pH
6. other ions

Question 2

what do stones likely result from?

Answer 2

nucleation + growth + aggregation from crystals

all aided by retention of urine

Question 3

is finding crystals in urine significant?

Answer 3

not necessarily. it just indicates urine is supersaturated which indicates a risk for urolith formation

Question 4

when are uroliths significant? if you see signs of….

Answer 4

1. secondary bacterial infection
2. obstruction
3. hematuria, pyuria (pus in urine)
4. urgency, stranguria, pollakiuria

Question 5

how do you diagnose uroliths?

Answer 5

imaging - contrast studies, endoscopy

Question 6

what are some treatment options for uroliths?

Answer 6

1. emergency tx
2. medical tx
3. catheter removal
4. urohydropropulsion
5. cytoscopic retrieval
6. lithotripsy
7. surgery

Question 7

describe emergency tx of uroliths. what is most impt?

Answer 7

tx hyperK and acidosis is most impt!

place IV catheter and start fluids then deal with the obstruction

Question 8

describe medical tx of uroliths. what is the overall goal?

Answer 8

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

Question 9

what tx is used for “sand” sediment?

Answer 9

catheter removal - flush, refill and repeat technique

Question 10

describe urohydropropulsion

Answer 10

fill bladder under anesthesia and express to achieve a forceful stream and collect for examination

Question 11

what is lithotripsy and what are the 2 kinds performed?

Answer 11

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

Question 12

which tx is most commonly performed for uroliths?

Answer 12

surgery is most common - usually a cystotomy

Question 13

when should preventative strategies be considered?

Answer 13

• recurrent urolithiasis
• nephro or ureterolithiasis
• no underlying cause
• underlying cause that cant be controlled

Question 14

what is a non-specific prevention?

Answer 14

increasing water consumption! it decreases the amount of mineral in urine and this is super impt!!

Question 15

what are the most common stone types?

Answer 15

1. struvites
2. urates (purines)
3. compound uroliths

Question 16

what are struvites and how are they usually treated?

Answer 16

they are the most common

• dogs with struvites will also have UTIs, cats will not
• will often respond to dissolution and pH modulation

Question 17

what type of acidifer should you use with struvites?

Answer 17

ammonium chloride for pH modulation

Question 18

when do you need the alter a diet long-term for a patient with struvites?

Answer 18

dogs with sterile struvites and cats

Question 19

do you need to give abx to patients with struvites?

Answer 19

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!!

Question 20

Calcium Oxalates - how are they treated? what are the risk factors for getting them?

Answer 20

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

Question 21

hydrochlorothiazide

Answer 21

• decrease ca excretion

- effect blunted with increased water consumption

Question 22

potassium citrate: what are its 2 actions and when should you consider using it?

Answer 22

1. pH modulation - urine alkalinizer
2. corrects hypocitraturia - decreases available ca in the urine

consider using when: diet and thiazides have failed and to achieve target pH

Question 23

does vitamin supplementation help prevent uroliths? Vit B6? Vit C? Vit D?

Answer 23

nope!
B6 - no data
C - avoid, can increase oxalates
D - avoid, potential for increase Ca

Question 24

purines - how are they treated?

Answer 24

check to make sure liver function is ok!

1. diet/pH modulation - decrease protein in diet and aim for a neutral to slightly alkaline pH
2. allopurinol - xanthine oxidase inhibitor. not recommended for prevention unless diets and alkalinization fail. not good for animals in liver failure.

Question 25

cystine: when do they occur? how are they treated?

Answer 25

• uncommon
• M»>F
• characterized by cystinuria
• frequently recurrent

Tx: decrease protein in diet and pH modulation

Question 26

what is the process of urolith formation? how does it start?

Answer 26

it starts by having urine be supersaturated.

precipitation –> nucleation –> cystallization aggregation