Kidney stones

What are kidney stones?

Your kidneys are part of your urinary system. Kidneys have several important functions including cleaning your blood to remove waste products into urine (wee).

Urine contains many waste chemicals which can clump together into hard crystals. These hard crystals are kidney stones. They can range in size from as small as a grain of sand to as big as a golf ball.

There are many types of kidney stones. They can be made from:

• calcium oxalate
• calcium phosphate
• uric acid
• cystine

Less common types of kidney stones are called struvite stones or cystine stones.

Kidney stones can be painful and are sometimes serious. You should see your doctor if you think you might have a kidney stone.

Other names for kidney stones are renal calculi, nephrolithiasis or urolithiasis.

What are the symptoms of kidney stones?

At first you may have no symptoms from a kidney stone.

Later you may notice pain as the stone moves from your kidney into your bladder or when you pass urine.

The kidney stone could cause a blockage in your urinary system.

You might feel a gripping pain in your back, side, lower belly or groin. This pain is called renal colic. The pain of kidney stones can be severe and lead to you feeling sick or vomiting.

If you have kidney stones, you may also:

• have blood in your urine
• feel nauseous
• have a fever, hot and cold shivers or sweats
• have bad smelling urine if you have an infection
• feel like you have gravel in your urine
• feel like you need to pass urine often or urgently
• see small stones in your urine

What causes kidney stones?

You’re more likely to get kidney stones if:

• you’ve had one before
• they run in your family (you may have inherited genes that increase your chance)
• you are male
• you are often dehydrated
• you take certain medicines
• you eat foods that are high in salt
• you have certain health conditions like
  • gout
  • urinary tract infections
  • inflammatory bowel disease
  • some cancers
  • a rare genetic metabolic condition

You may not find out what caused your kidney stones.

How are kidney stones diagnosed?

If you have renal colic pain your doctor can order tests to confirm the diagnosis of kidney stones.

You may also need to have:

• blood tests
• urine tests
• imaging tests — CT scan, ultrasound, or x-ray.

If you can collect a stone from your urine your doctor can send it for testing.

You may find out that you have kidney stones by chance. For example, during imaging tests that are being done for another reason.

How are kidney stones treated?

Your treatment will depend on what type and size of kidney stones you have.

You can take simple painkillers like paracetamol if your pain is mild. Drink plenty of clear fluid such as water. See your doctor if the pain is bad.

Small kidney stones (less than 5mm to 7mm) will often come out by themselves into your urine. This can take 3 to 6 weeks. You might be offered a medicine to help.

If you have a larger stone, you might need to see a surgeon. The surgeon can use ultrasound waves to break it up, or do an operation to remove it. There are several options available. Discuss these with your doctor.

Your doctor can prescribe antibiotics if your kidney stones are caused by a kidney or bladder infection.

Can kidney stones be prevented?

Here are some tips to help you can reduce the chance of getting kidney stones.

• Drink plenty of water or other fluids such as juice, milk, or tea.
  • You will know that you are drinking enough if your urine is a light straw colour.
• Eat a balanced healthy diet. You should eat a diet that is:
  • high in calcium
  • low in salt
  • low in protein
  • high in fibre
• Avoid urinary tract infections. If you get one, treat it quickly.

If you have had a kidney stone before, you can take a medicine to reduce the level of some chemicals in your urine.

Complications of kidney stones

If your kidney stones block your urinary system you will need to have treatment at hospital.