Renal stones Flashcards
85% of renal stones are what composition?
calcium oxalate
Calcium oxalate stones
1) hyper____ is a major risk factor
2) radio- LUCENT/ OPAQUE
1) calciuria
2) opaque
Renal stones associated with an inherited disorder?
Cystine
disorder of transmembrane cystine transport > decreased absorption of cystine from intestine and renal tubule
Uric acid stones
1) uric acid is a product of ___ metabolism
2) may precipitate when urinary pH is ____
3) radio_____
1) purine
2) low
3) lucent
renal stones caused by diseases with extensive tissue breakdown e.g. malignancy
uric acid stones
Calcium phosphate stones
1) may occur in renal __ __
2) renal tubular acidosis types __ and __ increase risk of stone formation
3) radio______
1) tubular acidosis (high urinary pH increases supersaturation of urine with calcium and phosphate)
2) 1 and 3 (not 2 and 4)
3) opaque (similar composition to bone)
staghorn calculi?
struvite
Struvite stones
1) formed from …..
2) occur as a result of ____ producing bacteria (and are thus associated with chronic ____) > produces alkaline conditions > crystals precipitate
3) slightly radio____
1) magnesium, ammonium and phosphate
2) urease, infections
3) opaque
state the urine acidity associated with the following stones
1) calcium phosphate
2) uric acid
3) struvate
4) cystine
1) normal- alkaline
2) acid
3) alkaline
4) normal
Radio-opaque or radiolucent?
1) calcium oxalate
2) mixed calcium oxalate/ phosphate
3) triple phosphate
4) calcium phosphate
5) urate
6) cystine
7) xanthine
1) O
2) O
3) O
4) O
5) L
6) semi-O
7) L
Stag-horn calculi
1) Involve the renal ___ and extend into at least 2 calyces.
2) They develop in ACIDIC/ ALKALINE urine and are composed of ______
3) which pathogen predisposes to their formation
1) pelvis
2) alkaline, struvite (ammonium magnesium phosphate)
3) proteus and ureaplasma urealyticum
radiographic appearance: semi-opaque, ‘ground glass’ appearance
cystine
risk factors for renal stones?
dehydration hypercalciuria, hyperparathyroidism, hypercalcaemia cystinuria high dietary oxalate renal tubular acidosis medullary sponge kidney, PKD beryllium or cadmium exposure
risk factors for urate stones?
gout
ileostomy (loss of bicarbonate and fluid > acidic urine)
drugs that promote calcium stones?
loop diuretics
steroids
acetazolamide
theophylline
what drug class can prevent calcium stones?
thiazides (increase distal tubular calcium resorption)
pain relief for renal colic?
IM diclofenac
initial investigations for renal stones?
urinalysis
CRP/
creatinine
Best investigation for renal stones?
non-contrast CT-KUB
sensitivity 97%, specificity 95%
when can renal stones be managed expectantly?
<5mm (will typically pass within 4 weeks of symptom onset)
Management
1) stone burden <2cm in aggregate
2) stone burden <2cm in pregnant females
3) complex renal calculi and staghorn calculi
1) Shockwave lithotripsy
2) Ureteroscopy
3) Percutaneous nephrolithotomy
prevention of calcium stones?
hydration
low animal protein and low salt diet
thiazide diuretics
prevention of oxalate stones?
cholestyramine and
pyridoxine reduce urinary oxalate secretion
prevention of uric acid stones?
allopurinol
urinary alkalisation e.g. oral bicarbonate
Management of renal stone <5mm causing ureteric obstruction and infection
surgical emergency > decompression with e.g. nephrostomy, ureteric catheter or stent
risks associated with Shockwave lithotripsy?
shock waves can cause solid organ injury
fragmentation of larger stones may result in ureteric obstruction
NB: analgesia required during and after
Shockwave lithotripsy vs Percutaneous nephrolithotomy?
Shockwave lithotripsy:
shock wave generated external to the patient, internally cavitation bubbles and mechanical stress lead to stone fragmentation.
Percutaneous nephrolithotomy: access gained to the renal collecting system then intra corporeal lithotripsy or stone fragmentation is performed and stone fragments removed.
