Stone Disease

Introduction

The kidneys’ job is to remove waste products from the body. Each kidney contains millions of tiny filter units, which remove waste chemicals and water; this waste passes down the ureters, into the bladder and is then passed out of the body when you go to the toilet. Because the kidneys are filtering all this waste, they are vulnerable to problems such as the formation of stones.



How are stones formed?
If the urine becomes concentrated, crystals start to form from the salts filtered by the kidneys. These crystals then clump together to form stones.

Common sites of stone blockages

• In the kidney
• In the ureter
• Just before the bladder

What are stones made of?

There are several salts which form stones:

• 75% of stones are made of calcium
• 8% of stones are made of uric acid
• 2% of stones are made of cystine
• 15% are a mixture of calcium, magnesium, ammonium and phosphate.

The mixed stones are more likely to become infected.

Who gets stones?

1 in 10 men will develop stones and 1 in 20 women. The most common age is between 30 and 50 years. Uric stones are more common in men.

When some has one stone they have a 50% risk of another within the next 10 years and a 2% risk of several episodes throughout life.

Why me?

There is no clear reason why one person should develop stones but another person with a similar lifestyle will not. However, it is known the condition can run in families.

Stones are more common in hot climates. This is probably because the body loses fluid by sweating, so the salts in the urine become concentrated. It therefore makes sense to drink more in hot weather.

So what can be done to prevent new stones forming?

• Increasing your fluid intake can reduce the risk by 70 to 90%.

• You need to drink enough fluid to produce 2 litres of urine per day. The urine should be pale yellow in colour.

• Reducing your salt intake may also help.

• You should eat a balanced diet but perhaps reduce the protein intake – talk to your doctor or nurse about this.

There is no evidence to show reducing dairy products is helpful. If you are vegetarian you may need some dietary advice and should discuss this with your specialist.

Whatever type of stone, the main message is drink plenty of water!