The cause of most stones is unknown, but they can be associated with a high concentration of calcium in the urine or occasionally in the blood. They can also be caused by dehydration, infection, obstruction of urine and various kidney disorders. Crystals of salts found normally in the urine aggregate together and gradually enlarge in size to form stones, which may vary greatly in size. Some are as small as a grain of sand whereas others are so big they fill the entire renal pelvis.

Kidney stones typically occur in healthy men aged between 30 and 50. The male to female ratio for kidney stone disease is 4:1.

Patients who have had stones before are more at risk of further stones and sometimes the problem runs in families.

What are the symptoms of kidney stones?

Kidney stones may cause sudden, intense pain. If the stone travels down the ureter (the tube leading from the kidney to the bladder) it may get stuck at one of several points. The pain that this causes is usually concentrated on one side of the back but may also move into the stomach or down to the groin where it can result in stabbing pains. The same type of pain may also be caused by bleeding or infection in the urinary system. Kidney stone attacks can be so painful they cause great distress to the sufferer. The pain is often accompanied by nausea and vomiting.

They may cause scratches in the lining (mucosa) of the renal pelvis or the ureter. This leads to blood in the urine. There is not always enough to be seen with the naked eye but a diagnostic test can detect it.

Frequent infections in the urinary system may be a sign of kidney stones.

What should you do if you have an attack?

If you have a kidney stone attack, you may need medical help to ease the pain if simple painkillers (for example ibuprofen) are not helpful.

If you have never had a stone before, investigations will be necessary to make a diagnosis because other serious abdominal problems may cause similar pain.

Stones less than 5mm are very likely to pass out of the ureter spontaneously. Once the stone reaches the bladder, it normally passes out of the body in the urine without further problems and often without you even being aware of it.

Larger stones may not pass on their own and may need an eswl lithotripsy to remove them.

The doctor may want to see the stones. They are obviously difficult to catch but one solution is to try urinating through a sieve.

Will you need to go to hospital?

If the kidney stone is so big that it cannot come out by itself or the pain continues, it will be necessary to go to hospital.

In the past X-ray or ultrasound were used but it is becoming more common to use a CT scan to diagnose the problem.

CT is very good at showing the size of the stone and where it is situated. This is important because it helps doctors decide how, and when, the stone should be removed. If the stone is small and lying close to the bladder, it may be left to pass on its own.

There are many modern methods of removing stones that involve passing a small telescope via the bladder through which a variety of stone disintegrators can be used. Occasionally, a small opening is made directly into the kidney for large stones. It is very rare nowadays for patients to need open surgery.

What is lithotripsy for kidney stones?

Lithotripsy uses shockwave therapy equipment to break up kidney stones. The treatment is performed in hospital using special equipment and is becoming more and more common.The stone is fragmented into pieces by the treatment and these smaller pieces can then pass out of the body unaided in the urine.

If the stone is larger than 1cm, then more than one treatment session may be required.