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HealthInfo Canterbury

Kidney stones & renal colic

Kidney stones are a common and painful medical problem. They happen when there are too many crystals in your urine, which stick together and form stones.

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

What causes kidney stones?

urinary system showing kidneys, ureters, bladder, and urethraThere are several reasons you might get kidney stones. Some happen because you have high levels of chemicals such as calcium, uric acid or oxalate in your blood. These lead to different types of kidney stones.

Calcium stones

Calcium stones are common. They happen if you have a lot of calcium in your blood. You are more likely to get calcium stones if you eat a lot of food that is rich in oxalate, such as potato chips, chocolate, peanuts, and beetroot.

Uric acid stones

These stones are more common in men than in women. They happen because your urine is too acidic and there is a lot of uric acid in your blood. You are more likely to get uric acid stones if you are dehydrated, or if you eat food that is rich in purines, such as fish, shellfish, and meat.

Struvite stones

These are more common in women who get repeated urinary tract infections (UTIs). They are made up of magnesium, ammonium, and phosphate.

Symptoms of kidney stones

Sometime people pass kidney stones in their urine, and have few symptoms. However, kidney stones can get stuck and cause a blockage. This is called renal colic, and can be very painful. The symptoms of renal colic include:

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

How are kidney stones diagnosed?

If doctors think you might have kidney stones, they will ask you to have some tests. These include:

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Written by HealthInfo clinical advisers. Endorsed by clinical director, Nephrology Department, Canterbury DHB. Updated September 2016.

Sources

In this section

You have a kidney stone, what will happen now?

Eating to prevent kidney stones

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