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Kidney Stones

This factsheet is for people who have kidney stones, or who would like information about them.

Kidney stones (or calculi) are hard stones that can form in one or both of the kidneys.

Click on the tabs below for more information about kidney stones.

Publication date: March 2009.

How extracorporeal shockwave lithotripsy is used to treat kidney stones

About

About

About kidney stones

You normally have two kidneys which clean your blood, and filter out water and waste products to make urine.

Small, solid crystals can form from the salts or minerals found in your urine. These crystals are often too small to notice, and pass harmlessly out of your body. However, they can build up inside your kidney to form a kidney stone. They are usually yellow or brown, and may be smooth or spiked.

Stones can move out of your kidney into the ureter – the tube that carries urine from the kidney to your bladder. A kidney stone can become stuck in the ureter causing pain, infection and occasionally kidney damage.

Kidney stones shouldn't be confused with gallstones, which don't affect the kidneys and are caused by raised cholesterol levels.

Complications of kidney stones

You may get damage to your kidneys and severe infection if you have a blockage. It's important that you seek urgent medical attention if you have any symptoms of kidney stones.

Causes of kidney stones

Men are more likely to get kidney stones than women. In most people, there is no obvious reason for developing kidney stones, although you may be more likely to get kidney stones if you:
  • have a family history of kidney stones
  • are aged between 20 and 50
  • are taking certain medicines – for example, indinavir (in the treatment of HIV infection) and certain diuretics
  • are taking too many vitamin C or calcium/vitamin D supplements, or antacids
  • have an abnormally shaped kidney
  • eat a lot of protein
  • are dehydrated because you don't drink enough fluids

Symptoms and diagnosis

Symptoms and diagnosis

Symptoms


Many kidney stones are too small to cause symptoms. But if a kidney stone causes a blockage, or moves into your ureter, you may:

  • have severe pain or ache on one or both sides of your back
  • get sudden spasms of excruciating pain – this usually starts in the back below your ribs, radiating around your abdomen, and sometimes to your groin and genitals
  • have bloody or cloudy urine
  • feel sick or vomit
  • need to urinate often, or feel a burning sensation during urination
  • get fever and chills
You can also have these symptoms if you have a urinary tract infection (UTI) or cystitis. If you have one or more of these symptoms, you should ask a doctor for advice.

The pain of kidney stones – called renal colic – can be very severe. It begins as soon as the stone becomes stuck in the ureter, and tends to come in waves. It's not usually associated with the size of the kidney stone – sometimes small stones can cause more pain than very large ones.

Small kidney stones are usually passed out of the body within a day or so and mostly within six weeks. Bigger stones are less likely to pass out of the body spontaneously. Stones greater than 5mm (a quarter of an inch) in diameter are the least likely to pass without medical help.

If you're pregnant and have any symptoms of kidney stones, see a doctor straightaway.

Diagnosis


The doctor will ask you about your symptoms and examine you. He or she may also ask you about your medical history. The doctor may do more tests to confirm the diagnosis and/or refer you to a urologist or an emergency department for tests. These will show the size, location and type of your kidney stone. The tests may include:

  • urine analysis – to look for signs of infection
  • blood tests – to identify excess amounts of certain chemicals which cause kidney stones
  • CT (computed tomography) scan – this uses X-rays to make a three-dimensional image of the area
  • intravenous urogram (IVU) – injection of a special dye that shows up the whole urinary system and any stones on X-ray images
  • ultrasound scan – this uses sound waves to produce an image of the internal organs
  • X-ray – stones that contain calcium usually show up white on X-ray images
Please note that availability and use of specific tests may vary from country to country.

Treatment and prevention

Treatment and prevention

Your treatment depends on the type and cause of your kidney stone. Most stones can be treated without surgery.

Your doctor may recommend home treatment. If your stone is smaller than about 5mm you can normally pass it in your urine. Make sure you drink enough water to stay hydrated. Your doctor may offer you medicines to reduce pain and sickness.

Your doctor may ask you to catch the kidney stone by passing your urine through filter paper or a tea strainer. The stone can then be analysed to find out what type it is, to help guide your treatment and prevent more stones.

If you have a kidney stone that hasn't passed out of your body within about six weeks, it's likely that you will need treatment.

Medicines


If your doctor thinks you have an infection then he or she will prescribe you antibiotics.

Your doctor may offer a medicine called an alpha-blocker to help the stone pass out in your urine. This is called medical expulsive therapy (MET).

Non-surgical treatments


Extracorporeal shock wave lithotripsy (ESWL) is the most common method of treating kidney stones that haven’t passed. A machine called a lithotriptor sends shock waves through the skin of your abdomen (tummy) to your kidney stone to break it up into crystals small enough to be passed in your urine. You may feel some pain as the stone breaks up, so the procedure is usually performed under sedation with a painkiller.

Surgery

Ureteroscopic stone removal

If your stone is lodged in the ureter, your surgeon will pass a narrow, flexible instrument called a cystoscope up through your urethra and your bladder. A laser beam or shock waves from a device on the cystoscope remove or break up the stone. A soft tube (stent) may be left in your ureter for a few days until it heals. Ureteroscopy is usually done under general anaesthesia. This means you will be asleep during the procedure. The stent is usually removed under local anaesthesia after three to 14 days.
Percutaneous nephrolithotomy (PCNL)

Large stones can be surgically removed from the kidney. Your surgeon makes a small cut in your back and uses a telescopic instrument called a nephroscope to pull the stone out or break it up using a laser beam or shock waves. PCNL is performed under general anaesthesia.

Prevention of kidney stones


If you have had a kidney stone, there are things you can do to prevent getting another. It's important that you don't become dehydrated. Increase the amount of water you drink, aiming for enough to make your urine clear rather than yellow. Drink plenty of fluids in hot weather, when you travel or if you have a fever. Talk to your doctor for more advice on this.

Also, make sure you don’t eat more than 3g of salt – don’t add it to your food and avoid processed foods.

Depending on the type of stone you have, there may be specific things you can to do to prevent another kidney stone. For example, if you get calcium oxalate stones you should cut down on foods that have high levels of oxalate. These include chocolate, tea, rhubarb, spinach and strawberries.

If you get uric acid stones, you should eat less meat, fish and poultry, and your doctor may prescribe medicines to help reduce levels of uric acid in your urine. Don’t take supplements containing vitamin C or D as these increase the amount of oxalate in your urine.

Your doctor may prescribe medicines to reduce the chance of you getting cystine stones.

To prevent struvite (or infection) stones, you need to take antibiotics if you get a urine infection.

Availability and use of different treatments may vary from country to country. Ask your doctor for advice on your treatment options.

Further resources

Further resources

  • Nephrolithiasis. eMedicine. www.emedicine.medscape.com, accessed 4 August 2010
  • Kidney Stones: Basic facts everyone should know. American Urological Association Foundation. www.urologyhealth.org, accessed 11 August 2010.
  • Renal colic - acute. Clinical Knowledge Summaries. www.cks.nhs.uk, accessed 4 August 2010
  • Gallstones (and associated conditions). Map of Medicine. www.mapofmedicine.com, accessed 4 August 2010
  • Kidney stones – suspected. Map of Medicine. www.mapofmedicine.com, accessed 4 August 2010
  • Urinary Calculi. The Merk Manuals. www.merck.com/mmhe, published August 2007
  • Stones – Management of ureteral stones. American Urological Association Foundation. www.urologyhealth.org, accessed 5 August 2010
  • Simon C, Everitt H, van Dorp F. Oxford handbook of general practice. 3rd ed. Oxford: Oxford University Press, 2010: 452-3
  • Guidelines on urolithiasis. European Association of Urology, 2010. www.uroweb.org
  • Extracorporeal shockwave lithotripsy. eMedicine. www.emedicine.medscape.com, accessed 4 August 2010
  • ESWL. British Association of Urological Surgeons. www.baus.org.uk, accessed 11 August 2010
  • Ureteral calculi. 2007 guideline for the management of ureteral calculi. American Urological Association, 2007. www.auanet.org
  • Urteroscopic stone removal. British Association of Urological Surgeons. www.baus.org.uk, accessed 5 August 2010
  • Aungst M, Sears C, Fischer J. Ureteral stents and retrograde studies: a primer for the gynecologist. Curr Opin Obstet Gynecol 2009; 21(5):434–41
  • Dietary advice for stone formers. British Association of Urological Surgeons. www.baus.org.uk, accessed 5 August 2010

This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. This content was compiled by Bupa based on clinical information and practice current as at the stated date of publication. Content is likely to reflect clinical practice in a particular geographical region (as indicated by the sources cited) – accordingly, it may not reflect clinical practice in the reader’s country of habitation. This content is intended for general information only and does not replace the need for personal advice from a qualified health professional. Photos and videos are only for illustrative purposes and do not reflect every presentation of a condition.

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