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Kidney stones

Kōwhatu tākihi

Kidney stones diagramYour kidneys act as your body's filtering system, absorbing the good chemicals and minerals and passing the unwanted ones in your wee (urine). If certain chemicals and minerals build up in the kidneys or in the wee, they can form a stone. Most stones are made of calcium oxalate, other types include uric acid, struvite (infected stones) and rarely, cystine.

These stones can be as small as a grain of rice or grow to be as large as an apple. They can happen anywhere in your urinary system, such as your kidneys, one of the tubes that drain wee from your kidneys (called your ureters) or your bladder.

The stones may stay in the kidney or travel down the ureter into the bladder. This is when they cause pain.

Causes of kidney stones

Kidneys stones are usually caused by a combination of factors.

Things that increase your risk include:

Symptoms of kidney stones

You may have no symptoms from a kidney stone, especially if it's small or not moving down from the kidney.

The symptoms when a stone is moving (renal colic) include:

If you have any of these symptoms, see your general practice team or after-hours healthcare provider as soon as possible for tests and pain relief. If you're very unwell, you may need to go to hospital.

Diagnosing kidney stones

If your doctor thinks you might have kidney stones, they will ask you about your symptoms and do a physical examination. They may then ask you to have some tests. These include:

Treating kidney stones

Your treatment will depend on the size of your stone and where it's sitting.

If the stone is small, it will most likely pass out by itself. But if it's large, you may need surgery or another treatment to remove it. Generally, it's better if the stone passes on its own as this avoids the need for any surgery.

Treatment to help small stones pass

If you have a small stone, you will not normally need to go to hospital. Your doctor will advise you to drink a lot of water. As well, they may prescribe:

Your doctor may ask you to sieve your urine and give them any stone you pass so it can be tested to find out what type of stone it is.

Treatment to remove larger stones

If your stones are very large, they can be removed by:

After your treatment, if you get severe pain that doesn't respond to pain relief tablets or you have vomiting or a fever, go to your doctor, an after-hours doctor or the Emergency Department.

Preventing kidney stones

The best thing you can do to reduce your risk of kidney stones is to drink plenty of fluids. Aim for 10 to 12 cups a day. Water is best. For tips about making sure you get enough fluid, read How to get enough to drink.

More advice to prevent kidney stones is on the next page.

  HealthInfo recommends the following pages

On the next page: Preventing kidney stones

Written by HealthInfo clinical advisers. Last reviewed April 2023.

Sources

Page reference: 47528

Review key: HIKIS-19017