Urinary tract calculi Flashcards
Types of renal stones
Calcium oxalate
Cystine
Uric acid
Calcium phosphate
Struvite
Calcium oxalate stones
Most common
Hypercalciuria is major risk factor
Stones are radio-opaque
Cystine stones
Inherited recessive disorder of transmembrane cystine transport leading to decreased absorption of cystine
Multiple stones may form
Relatively radiodense because they contain sulphur
Uric acid stones
Uric acid is product of purine metabolism
May be caused by diseases with extensive breakdown (malignancy)
More common in children with inborn errors of metabolism
Radiolucent
Calcium phosphate stones
May occur in renal tubular acidosis
High urinary pH increases supersaturation of urine with calcium and phosphate
Radio-opaque stones (composition similar to bone)
Struvite stones
Formed from magnesium, ammonium and phosphate
Occur as a result of urease producing bacteria
Slightly radio-opaque
Staghorn calculus
Stones form in the shape of the renal pelvis
Most commonly occurs in stones made of struvite
Presentation
Renal colic (colicky loin to groin pain)
Haematiuria
Nausea or vomiting
Reduced urine output
Symptoms of sepsis if infection present
Investigations
Urine dip (haematuria)
Bloods for infection and calcium
Abdominal xray shows calcium based stones
Non-contrast CT KUB within 24 hours of presentation
US if pregnant or children
Management
Watch and wait if <5mm
NSAIDs (IM diclofenac)
Antiemetics
Antiobitcs
Tamsulosin to help aid spontaneous passage of stones
Surgical intervention
Surgical interventions
Extracorporeal shock wave lithotripsy
Ureteroscopy and laser lithotripsy
Percutaneous nephrolithotomy
Recurrent stones
Increase oral fluid intake
Add fresh lemon juice to water
Avoid carbonated drinks
Reduce dietary salt intake
Maintain a normal calcium intake
Dietary recommendations
Calcium stones- reduce oxalate rich foods (spinach, beetroot, nuts, rhubarb, black tea)
Uric acid stone- reduce purine rich foods (kidney, liver, anchovies, sardines, spinach)
Limit dietary protein
Medications to reduce risk of recurrence
Potassium citrate or thiazide diuretics in patients with calcium oxalate stones and raised urinary calcium
