Urinary Stones (Kidney Stones)

• The most common, accounting for >80% of all stones. 
• Most are in the form of calcium oxalate. Oxalate is found naturally in many foods, and foods with high oxalate content include peanuts, beans, leafy vegetables and chocolate. 
• Another major group are calcium phosphate stones, which are usually associated with metabolic diseases, including hyperparathyroidism and renal tubular acidosis.

• Drinking water. You should drink enough water to produce light and clear urine.
• Reduce intake of oxalate-rich foods. These include spinach, sweet potatoes, nuts, tea, chocolate, and soy products.
• Reduce salt and protein in your diet.
• Continue eating calcium-rich foods, but use caution with calcium supplements. You may reduce the risk of stone formation by taking supplements with meals. Diets low in calcium can also increase kidney stone formation in some people. If in doubt, please consult your doctor or a dietician.

• Age: Usually more common in older individuals ~40 – 60 years of age.
• Obesity: Has been associated with >50% higher risk of stone formation.
• Genetic: A history of kidney stones within the family is associated with a higher risk.
• Dehydration: A lack of fluid intake leads to concentration of salts in the urine, increasing risk of stone formation.
• Diet: Certain diets high in oxalate (nuts, long beans, chocolate), high in purines (red meat, organs, seafood).
• Previous kidney stones: An individual with a diagnosed kidney stone has a 50% risk of developing another stone within the next 10 years.
• Certain medical conditions: Diabetes, metabolic syndrome, hyperparathyroidism, renal tubular acidosis, gastrointestinal diseases (including inflammatory bowel disease, malabsorption, bariatric surgery, previous intestinal resections). Known conditions associated with urinary tract obstruction can also increase the risk of stone formation.
• Use of certain medications: HIV medications (indinavir).

When to see a doctor

• Drinking water: Drink as much 2-3 litres of water a day to keep your urine diluted and clear unless your doctor tells you otherwise.
• Pain relief: You may be prescribed pain medications to minimise discomfort during stone passage.
• Medical therapy: An alpha blocker, such as tamsulosin, may be prescribed to relax to muscles in your ureter, facilitating passage of stone with less pain.

• Extracorporeal shockwave therapy (ESWL): ESWL uses sound waves delivered by an external device that resembles an X-ray machine that break stones into smaller pieces that can be passed out in your urine. You will be given painkillers to make you more comfortable.
  
  ESWL may cause blood in urine, pain or bruising of your back or abdomen, bleeding around the kidney. Sometimes you may require more than one session to completely fragment the stones. Very rarely, the small fragments may be stuck in the ureter and cause obstruction of urine flow, which will require surgical management.
  
  
• Ureteroscopy: A small telescope can be passed through your urethra and bladder to your ureter. Tools can be used to break stones into pieces that will be removed with a small basket or pass out in your urine. You will require general anaesthesia during this procedure. Your doctor may then place a stent (small plastic tube) in the ureter to prevent swelling and obstruction of the ureter and to promote healing.
  
  You may require more than one procedure to completely remove larger stones. If your ureter is too tight to pass the ureteroscope or instruments through, your doctor may choose to insert a stent in your ureter to allow muscles in your ureter to relax and you will come back another day (~1-2 weeks) to complete the procedure.
  
  
• Percutaneous nephrolithotomy (PCNL): This procedure involves a small incision over your back and inserting a telescope and instruments into the kidney to break the stones into smaller pieces. This procedure requires general anaesthesia. You may wake up with a tube behind your back to help drain the urine and stone fragments. This will be removed in 1-2 days before you are discharged home.
  
  Potential complications of PCNL include bleeding, urinary tract infection, injury to adjacent organs and retained stones.