Key points Risk factors for recurrent kidney stones

    * Low urine volume
    * Elevated urinary oxalate excretion
    * Elevated urinary calcium excretion
    * Elevated urinary uric acid excretion
    * Low urinary level of inhibitors of stone formation, particularly citrate
    * Low or high urine pH
    * Urine stasis and infection

Considerations for referral for specialist evaluation

    * Young age (children)
    * Strong family history of kidney stones
    * Radiographic identification of multiple stones, anatomic abnormalities or nephrocalcinosis
    * Cystine or uric acid stones revealed by laboratory analysis
    * Presence of infected stones
    * Requirement for surgical intervention (including extracorporeal shock wave lithotripsy)

General measures to prevent recurrence of stones

    * Increase fluid intake to produce 2-3 L of urine daily
    * Decrease dietary oxalate (spinach, rhubarb, chocolate, nuts, cranberries)
    * Decrease intake of animal protein
    * Restrict sodium (< 100 mmol/d [ 2-3g/d]) rather than calcium (should be 1 g/d)

Indications for surgical removal of stones

    * Nonprogression of ureteric stones
    * Persistent obstruction
    * Persistent symptoms
    * Presence of infection

Last updated Dec 12/06