Kidney Stones Flashcards
Where do renal stones form?
What is the basis for stones to form?
When do they become symptomatic?
In the renal pelvis
Over-saturated urine leading to increased consentration of stone constituents
Symptomatic when:
-irritate or become stuck in ureters
What are the different types of renal stones?
What are key features of these stones?
Calcium-based stones (most common)
- calcium oxalate
- calcium phosphate
- associated with hypercalcaemia
Uric acid
- not visible on xray= radiolucent
- due to increased serum levels of purine i.e. high red meat consumption or haematological disorder
Struvite
-produced by bacteria due to bacteria hydrolysing urea in urine to ammonia which goes on to form solifd struvite
Cystine
-associated with AR disease cystinuria
What is a staghorn calculus?
When do they most commonly form?
When stone forms in shape of renal pelvis with horns extending into renal calyces
Struvite stones -> therefore recurrent UTI can be a risk factor for their development
How might someone with renal stones present?
Renal colic:
- unilateral loin to groin pain= EXCRUCIATING
- colicky= fluctuating severity
- restless + unable to lie still due to the pain
Haematuria
N+V
Reduced urinary output
Sepsis if infection occured
Why does renal colic present with colicky pain?
Due to the stone moving and settling which leads to the fluctation in severity of the pain
What are the 3 most common locations for stones to become lodged?
Pelvicoureteric junction (PUJ)
Pelvic brim
Uretero-vesical junction
What are risk factors for developing renal stones?
Dehydration-> concentrates + saturates the urine
Previous calculi
Hypercalcaemia
Hyperuricaemia i.e. gout or CKD
Homocysteinuria
Structural abnormalities of UT i.e. strictures
Female
<65yo
How would you investigation someone suspected of renal stones?
Urine dip
- haematuria
- exclude infection
Blood tests
- FBC-> rule out infection
- U+Es-> kidney function/calcium levels
AXR
-calcium based stones
Non-contrast CT KUB
-gold standard for investigation stones
US KUB
-helpful in pregnant women + children over the CT scan
What is the typical presentation of hypercalcaemia?
What are the 3 main causes?
“Renal stones, painful bones, abdominal groans and psychiatric moans”
Calcium supplementation
Hyperparathyroidism
Cancer i.e. myeloma/breast cancer/lung cancer
How are renal stones managed medically?
Analgesia
- NSAIDs-> IM diclofenac
- IV paracetamol when NSAIDs not suitable
Antiemetics
-Metoclompramide
Abx if infection indicated
Watchful waiting
-when stone <5mm, likely they will pass without intervention (can take weeks for stone to pass)
Tamsulosin (alpha blocker)
-can help with spontaneous passage
What are the 3 indications for surgical intervention for stones?
What are the surgical options?
Stone >10mm
Stones which don’t pass spontaneous
Complete obstruction or infection
Extracorpeal shockwave lithotripsy (ESWL)
-shockwaves directed at stone under Xray guidance to break them up so they can be passed
Ureteroscopy + laser lithotripsy
- camera inserted via urethra and guided to site of stone
- targeted lasers break up the stones
Percutaneous nephrolithotomy (PCNL)
- under GA
- nephroscope insert via incision in back and guided to stone to break into pieces
What lifestyle advice should someone by given to avoid recurrent stones?
Increase oral intake
Add lemon juice to water
-citric acid binds urinary calcium to reduce formation of stones
Avoid carbonated drinks
-cola contains phosphoric acid= promotes calcium oxalate formation
Reduce dietary salt intake
Maintain normal calcium intake
Reduce intake of oxalte rich food i.e. spinach/beetroot/nuts/rhubarb
Reduce intake of purine rich foods i.e. kidney/liver/anchovies/sardines
Limit dietary protein
What medications can be used to decrease the risk of stone recurrence?
When patients had calcium oxalate stones and have raised urinary calcium
Potassium citrate
Thiazide diuretics
