Urinary Tract Calculi Flashcards
List 4 general risk factors for stones?
- Dehydration
- High dietary oxalate
- Renal tubular acidosis
- Polycystic kidney disease
List the 2 key complications of kidney stones?
- Obstruction leading to AKI
- Infection with obstructive pyelonephritis
What is the most common type of stone?
List the 2 types?
Calcium-based stones
- Calcium oxalate (more common)
- Calcium phosphate
List 2 key risk factors for calcium stones
- Hypercalcaemia
- Low urine output
How does hypercalcemia present?
Renal stones, painful bones, abdominal groans and psychiatric moans
List 2 drugs which precipitate calcium stones
- loop diuretics
- steroids
- acetazolamide
- theophylline
List the 3 key causes of hypercalcemia
- Calcium supplementation
- Hyperparathyroidism
- Cancer (ie. myeloma, breast or lung cancer)
Which drug may prevent calcium stones?
Thiazides (increase distal tubular calcium resorption)
List 3 other types of kidney stones
- Uric acid (not visible on x-ray)
- Struvite
- Cystine
List 2 risk factors for urate stones
- gout
- ileostomy (loss of HCO3 and fluid results in acidic urine)
What are Struvite stones associated with?
Produced by bacteria, therefore, associated with infection
What are the components of a Struvite stone?
Magnesium, ammonium and phosphate
What are Cystine stones associated with?
Associated with cystinuria, an autosomal recessive disease
What is a Staghorn Calculus?
Stone forms in the shape of the renal pelvis and extends into at least 2 calyces
(resemble antlers of a deer)
Staghorn Calculus occur most commonly with what type of stone?
Why?
Struvite
In recurrent upper UTIs, bacteria hydrolyse urea in urine to ammonia, creating struvite
Which stones appear opaque on X-ray?
- Calcium Oxalate
- Mixed calcium/ oxalate phosphate
- Stag-horn calculi
- Calcium phosphate
Which stones appear radio-lucent on X-ray?
- Urate stones
- Xanthine stones
How do cystine stones appear on x-ray
Semi-opaque, ‘ground glass’ appearance
How do renal stones present?
Renal colic (excruciating unilateral loin to groin pain which is colicky) +/-
- Haematuria
- Nausea or vomiting
- Reduced urine output
- Symptoms of sepsis, if infection is present
Initial Imaging of choice for Renal stones?
Non-contrast CT KUB should be performed on all patients within 24 hours of admission
List 4 other initial investigations for suspected stones
- urine dip and culture
- Renal function (serum creatinine + electrolytes)
- FBC / CRP
- calcium/urate
Management of kidney stones < 5mm
Will usually pass spontaneously within 4wks
Tamsulosin (alpha-blocker) can help aid the spontaneous passage of stones
Management in patients with obstructive stones with signs of infection?
URGENT renal decompression + IV antibiotics
(Options incl nephrostomy tube, ureteric catheters and ureteric stent)
What is the treatment of stones > 10 mm In the non-emergency setting?
- Extracorporeal shock wave lithotripsy (ESWL)
- Percutaneous nephrolithotomy (PCNL)
- Ureteroscopy and laser lithotripsy
- Open surgery (rarely used)
What is the analgesia of choice for kidney stones?
NSAIDs eg. IM diclofenac
(IV paracetamol is an alternative to NSAIDs)
Advice to give patients to prevent Recurrent Stones
- Increase fluid intake (2.5 – 3 litres/day)
- Reduce dietary salt intake (< 6g per day)
- Add fresh lemon juice to water
- Avoid carbonated drinks
- Maintain a normal calcium intake
List 2 foods you may recommend patients with calcium stones to AVOID
Oxalate-rich foods
eg. spinach, beetroot, nuts, rhubarb and black tea
List 2 foods you may recommend patients with uric acid stones to AVOID
Purine-rich foods
eg. kidney, liver, anchovies, sardines and spinach
List 2 medications which may be used to reduce the risk of recurrence in patients with calcium oxalate stones
- Potassium citrate for calcium oxalate stones
- Thiazide diuretics (e.g., indapamide)
List 2 medications which may be used to reduce the risk of recurrence in patients with uric stones
- Allopurinol
- Oral bicarbonate
