Urolithiasis (Yr 4) Flashcards
what are the top three uroliths?
struvite
calcium oxalate
cystine
what appearance do calcium oxalate dihydrate crystals have?
envelopes
what appearance do struvite crystals have?
coffin lids
what appearance to rate crystals have?
thorny apples
what appearance do cystine crystals have?
hexagons
what are the first tests to run when uroliths are identified?
USG and pH
(culture - possible UTI)
what uroliths form in acidic conditions?
calcium oxalate
purines
cystine
what uroliths for in alkaline urine?
struvites
what uroliths can be treated medically?
struvite
urate
cystine
(all dissolve with diet/therapy)
what are indications for surgical removal of calculi?
obstructions
increase in size/number of calculi
persistent clinical signs
lack of response to therapy
what pH does struvite form in?
alkaline
what is the predisposing factor which has to be present for struvite uroliths to form?
UTI (in dogs)
can struvites be seen on radiographs?
yes (radiopaque)
why does a UTI cause struvite stones?
urease produced by bacteria causes production of ammonia and bicarbonate from urea which cause pH to fall and irritation of the wall leading to cells being shed and forming the centre of a urolith
how are struvite crystals treated?
reduced protein, phosphorus and magnesium diet that promotes acidic urine
treat UTI
how is struvite dissolution monitored?
urinalysis and imaging for 4-6 weeks
(USG <1.020 and reducing stone size)
how can we prevent struvite?
prevent UTIs - treat infections when they arise
(don’t need lifelong dietary change)
what pH does calcium oxalate form in?
neutral/acidic
what is a predisposition for calcium oxalate formation?
hypercalcaemia
can calcium oxalate be seen on radiography?
no - radiolucent
are calcium oxalate more common in males/females?
males
how are calcium oxalate uroliths treated?
remove them physically
do calcium oxalate crystals recur?
yes (most will come back)
how can calcium oxalate uroliths be prevented?
prevent predispositions - hypercalcaemia, metabolic acidosis, vitamin D excess
increase urine output - decrease concentration of urine
what are urate crystals associated with
certain breeds (Dalmatian)
portosystemic shunts
what pH do urates form at?
acidic
can urates be seen on radiography?
no - radiolucent
how can urate uroliths be treated?
low protein, purine, alkaline producing diet (medical dissolution)
continue this diet life long
can cystine be seen on radiography?
no - radiolucent
what predisposes a dog to cystine?
males (androgen linked)
what uroliths can be treated medically?
struvite, urate, cystine
