What is kidney stones?

Small stones leave the kidney as the urine carries them out of the body. If stones stay in the kidney, they may grow larger. They can become stuck in the ureters, the tubes that carry urine from the kidney to the bladder. This causes pain. Some larger stones need medical treatment.

The four main types of kidney stones are:

Calcium stones.

Most kidney stones are made of calcium compounds. Conditions that cause high calcium levels in the body, such as hyperparathyroidism, increase the risk of calcium stones.

Uric acid stones.

Some kidney stones are made of uric acid, a waste product in urine. You're more likely to have uric acid stones if you have:

• Low urine output.
• A diet high in animal protein, such as red meat.
• An increase in how much alcohol you drink.
• Gout.
• Inflammatory bowel disease.

Struvite stones.

Some kidney stones are struvite stones. These can be serious, because they are often large stones and may occur with an infection.

Cystine stones.

Stones made of a chemical called cystine are less common. They're more likely to occur in people who have a condition that results in too much cystine in the urine (cystinuria).

For most stones, your doctor will recommend home care, such as pain medicine and drinking plenty of water. You may get a medicine to help the stone pass. If it is too large to pass, you may need other treatment, such as one that uses shock waves to break the stone into small pieces.

You can help prevent kidney stones by drinking plenty of water. Try to drink about 8 to 10 glasses a day. Eating less of certain foods may also help. Your doctor may give you medicine that helps prevent stones from forming.

Kidney stones may be diagnosed when you see your doctor or go to an emergency room with pain in your belly or side. Your doctor will ask about your symptoms and examine you.

Your doctor may do tests to help diagnose kidney stones and see where they're located. Tests include:

• A noncontrast spiral CT scan. This is a special type of CT scan that moves in a circle.
• An ultrasound exam (ultrasonogram). This uses reflected sound waves to examine your urinary tract.
• An intravenous pyelogram (IVP). This is an X-ray test that shows pictures of the urinary tract and kidney stones.
• A retrograde pyelogram. This uses a dye to check whether a kidney stone or something else is blocking your urinary tract.
• Urinalysis and urine cultures. These test your urine.
• An abdominal X-ray (KUB). This creates a picture of the kidneys, the bladder, and the tubes that connect the kidneys to the bladder (ureters).

Drinking more fluids and taking pain medicine are often the only things you need to do when you pass a kidney stone. Drink enough water. Over-the-counter pain medicine, like aspirin and ibuprofen, may help relieve your pain.

Several things can affect your risk for getting kidney stones. These include:

• How much fluid you drink. The most common cause of kidney stones is not drinking enough water.
• Your diet. Diets high in protein and sodium increase your risk for kidney stones. So do oxalate-rich foods, such as dark green vegetables. If you think that your diet may be a problem, a dietitian can help.

• Being overweight. This can cause both insulin resistance and increased calcium in the urine, which can increase your risk for kidney stones.
• Medicine. Some medicines can cause kidney stones to form.

Your age, gender, and whether you have a family history of kidney stones can also affect your risk. But these things are out of your control.

Kidney stones form when a change occurs in the normal balance of water, salts, minerals, and other things in urine. The most common cause is not drinking enough water. Some people are more likely to get kidney stones because of a medical condition, such as gout. They may also be an inherited disease.

Kidney stones are small "pebbles" that form in your kidneys. They're made of salts and minerals in the urine. They may stay in your kidneys or exit your body through the urinary tract. A stone traveling through a ureter—a tube that connects the kidney to the bladder—usually causes pain and other symptoms.