
Urinary tract stones are common. They may occur in the kidney, ureter or bladder. The symptoms are variable and include loin pain, infection and haematuria. Sometimes the stones are silent and are only discovered on a radiograph.
Types of stones:
1.Calcium oxalate stones
85% of urinary tract stones are calcium oxalate stones. They can be seen easily radiologically. Patients with this type of stone should avoid taking food rich in oxalate and these include peanuts, coffee, tea, strawberry, spinach.
2. Uric acid stones
5-15% of urinary tract stones. Pure uric acid stones are radiolucent and is difficult to be detected in a plain radiograph. Patients should avoid food rich in urate like seafood, red meat, kidney, liver, beans etc.
3.Phosphate stones
Usually calcium phosphate but sometimes combine with ammonium and magnesium. Occurs in alkaline urine and can grow to a very large size.
4. Cystine stones
It is rare and occurs in patients with genetic abnormality in cystine transport.


The Hong Kong Urology Clinic provides comprehensive assessment and treatment for patients with urinary tract stone disease. The following diagnostic tests may be required after your consultation with our urologists:
- Urinalysis and culture: to look for any urinary tract infection, which has to be treated before stone treatment
- XR kidneys, ureters and bladder (KUB): to look for any calcium oxalate and/or phosphate stones
- Ultrasound scan: to look for any obstruction of the urinary system caused by the stone(s)
- Renal function test, serum urate, calcium and phosphate tests: to look for any abnormal blood parameters suggestive of the cause of the stone disease
- CT imaging of the urinary tract: to look for any radiolucent stones, and relationship with other structures
