Kidney Stones Flashcards
What are the two key complications of kidney stones?
Obstruction
Leading to AKI
Infection
With obstructive pyelonephritis
What is the most common type of kidney stone?
Calcium-based stones
- Calcium oxalate (more common)
- Calcium phosphate
What are the risk factors for calcium stone formation?
Raised serum calcium
Low urine output
Asides from calcium-based stones, what other types of kidney stones are there?
Uric acid
Not visible on x-ray
Struvite
Produced by bacteria- associated with infection
Cystine
Associated with cystinuria- autosomal recessive disease
What is a staghorn calculus?
Stone forms in the shape of the renal pelvis
Body sits in the renal pelvis with horns extending into renal calyces, seen on x-ray
What are staghorn calculi stones commonly made of?
Struvite
In recurrent upper urinary tract infections, bacteria can hydrolyse urine to ammonia, creating solid struvite
Proteus Mirabilis
What is renal colic?
Presenting complaint in symptomatic kidney stones
Unilateral loin to groin pain
Colicky (fluctuating severity) as stone moves and settles
How can kidney stones present?
Renal colic
May also be:
- Haematuria
- Nausea or vomiting
- Reduced urine output
- Sepsis symptoms if infection is present
What investigations can be used for kidney stones?
Urine dipstick
Blood tests
AXR (can show calcium stones as they are radiolucent)
CT KUB (non-contrast) NICE recommend within 24 hours of presentation
Ultrasound KUB, negative result does not exclude stones
How are kidney stones managed?
NSAIDs
-Intramuscular diclofenac, IV paracetamol is an alternative if NSAIDs unsuitable
Antiemetics
Antibiotics
Watchful waiting
-If the stone is < 5mm 50-80% chance they will pass
Tamsulosin
Surgical intervention
What surgical interventions are available for kidney stones?
Extracorporeal shock wave lithotripsy
Shockwaves directed at stone under X-ray guidance, breaks up stones
Ureteroscopy and laser lithotripsy
Camera into urethra, bladder and ureter to identify stone
Stone broken up by lasers
Percutaneous nephrolithotomy
General anaesthetic- nephroscope inserted via patient’s back
Scope inserted into kidney to look at ureters, stones broken into smaller pieces and removed
What does NICE advise after one episode of renal stones?
- Increased fluid intake
- Add lemon juice to water (citric acid binds to urinary calcium)
- Avoid carbonated drinks (phosphoric acid promotes calcium oxalate formation)
- Reduce salt intake
- Maintain normal calcium (Low calcium increases kidney stones risk)
What recommendations are there for calcium renal stones?
Reduce intake of oxalate-rich foods e.g.
- Spinach
- Beetroot
- Nuts
- Black tea
What recommendations are there for uric acid stones?
Reduce purine intake e.g.
- Kidney
- Liver
- Anchovies
- Spinach
What medications limit risk of recurring kidney stones?
Potassium citrate
Calcium oxalate stones and raised urinary calcium
Thiazide diuretics
Calcium oxalate stones and raised urinary calcium
