THE URINARY TRACT SYSTEM
The urinary tract begins in the kidneys where urine is produced. Urine then drains through the ureters and stored in the urinary bladder until it is passed out through the urethra.

1. WHAT IS A KIDNEY STONE?
A kidney stone is a solid mass which forms in the urinary tract due to crystallisation of substances present in the urine and can be found along any part of the urinary tract. Kidney stones may stay in the kidneys or break loose and travel down the urinary tract. A small stone may pass out of the body spontaneously. On the other hand, a larger stone may become lodged in the ureter, bladder or urethra. Stones may also obstruct the flow of urine and cause pain although many can exist without symptoms. Stones that obstruct or cause repeated or severe infections may lead to kidney failure.

2. HOW DO KIDNEY STONES FORM?
Many risk factors lead to stone formation . Some of these include:

Drinking too little fluid
Family history of stones
Previous history of urinary tract infections or stones
Certain metabolic conditions

3. TYPES OF STONES
There are four main types :

Calcium Containing Stones (most commonly calcium oxalate)
     These may form for a variety of reasons including low fluid intake, high excretion of calcium, uric acid and/or      oxalate in the urine. A high amount of dietary salt also leads to increased calcium in the urine.

Infection Stones
     These are of a mixed nature containing magnesium ammonium phosphate (also called struvite) and calcium      carbonate. They are associated with infection by certain bacteria only.

Uric Acid Stones
     Too much acid in the urine assists in the formation of uric acid stones. Uric acid stones may also occur with      high quantities of uric acid passed in the urine.

Cystine Stones
     These are very rare and usually an inherited disorder.

4.  WHAT ARE THE SIGNS AND SYMPTOMS?
There may not be any symptoms at all. Symptoms of stone disease include the following:

  Pain at the side or back
  Blood in urine
  Painful urination, cloudy urine or urine that smells bad
  Fever usually suggests an associated infection

5. WHAT TESTS ARE USUALLY DONE TO CONFIRM THAT STONES ARE PRESENT?
A plain X ray of the urine tract called the KUB X-ray ( K idney – U reter – B ladder) can pick up about 85% of stones. These will be stones that contain calcium. Stones that do not contain calcium cannot be seen on a routine X-ray. Your doctor may order an IVU (intravenous urogram) instead which involves a dye being injected into the blood stream to “light up” the whole urine tract as the dye gets excreted. This can also detect obstruction to urine flow, if present. A less informative but easier alternative is an ultrasound scan.

6.  HOW TO FIND OUT WHAT TYPE OF STONES I HAVE?
The best way to find out what type of stones you have is to analyse the stone. If you know you are passing out a stone, you may catch it with a strainer and show it to your doctor. Other methods include a urine collection to look for abnormally high levels of the common constituents of stones. Blood tests may also be needed.

7.  WHAT NEEDS TO BE DONE WHEN A KIDNEY STONE HAS BEEN DIAGNOSED?
Your doctor will need to:

a) Assess your kidney function to check if there has been any kidney damage

b) Decide on what to do with the stone that has already formed
     Small stones which are causing no symptoms may be left alone. Small stones which are not obstructing and      appear to be passing down the urine tract may be left alone to give it an opportunity to pass out on its own.      However, if your doctor judges that it needs to be removed, he can choose one of the following options      depending on the size, type and location of the stone. Each treatment has its advantages and disadvantages.

	Extracorporeal Shock Wave Lithotripsy (ESWL) is a non invasive method using shock waves
	Percutaneous lithotripsy with an endoscope inserted into the kidney with energy applied directly to the stone.
	Endoscopic lithotripsy for ureteral or bladder stones

Open surgery is now seldom done though it may still be necessary for large stones.

c) Discuss with you measures to preventing new stones from forming

These measures should be taken once a stone has been detected. They include:

Keeping a high fluid intake
This will prevent saturation of urine with substances which can form stones leading to crystallisation and eventual stone formation.

	Dietary restrictions
-	Limiting sodium in the diet (to 2-3 g per day) to reduce urine calcium excretion
-	Reduce a high calcium intake to a moderate calcium intake. A low calcium intake is not advisable because of the risk of osteoporosis (thin bones)
-	Limiting the intake of coffee, tea, cola because they are rich in oxalate which can combine with calcium to ‘crystallize' and form stones
-	You may be advised to eat less meat if you have uric acid stones

The assistance of a dietician is useful in assessing what is considered optimal for a patient.

POINTS TO REMEMBER
1)  Untreated kidney stones can lead to kidney failure
2)  See a doctor if you have
     - severe pain in your back or side that will not go away
     - blood in the urine
3)  Talk to your doctor about how to avoid more stones
4)  Keep yourself well hydrated to prevent stone formation