Composition of urinary tract stones

The various types of renal stone are listed below:

• calcium oxalate stones:
  • 80% of all stones
  • radio-opaque
  • solitary, hard and white
  • require alkaline urine
    
    
• triple phosphate stones:
  • 10% of all stones
  • radio-opaque
  • may fill the calyceal system (Staghorn calculi)
  • require very alkaline urine, often with urea-splitting bacteria
    
    
• uric acid stones:
  • 5-10% of all stones
  • radio-lucent
  • multiple
  • associated with gout and other causes of urate nephropathy e.g. chemotherapy for leukaemia
    
    
• cystine stones:
  • rare
  • radio-opaque
  • usually seen in patients with cystinuria