Definition

Kidney stones form inside the kidneys or other parts of the urinary tract. They are made form a crystal-like substance. There are different types of kidney stones.

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Causes

The cause will vary with the type of stone:

• Calcium oxalate or phosphorus stones may form if there are:
  • High amounts of calcium or other minerals in the urine
  • Low levels of minerals that stop stones from forming
• Struvite stones may form with a urinary tract infection (UTI).
• Uric acid stones are caused by acid in the urine. They may also be caused by gout or chemotherapy.
• Cystine stones are caused by a rare genetic disorder. It causes a buildup of cystine which leads to stones.

Risk Factors

Kidney stones are more common in men under 50 years old or anyone with:

• Past kidney stones
• Family history of kidney stones
• Infections
• Bedrest

Calcium oxalate or phosphorus stones are more common in those with:

• High amount of sodium and oxalate in your diet (oxalate can be found in green, leafy vegetables, chocolate, nuts, or tea)
• Not drinking or keeping enough fluids and dehydration
• Overactive parathyroid gland
• Long term gut disorders such as Crohn disease or ulcerative colitis
• Diuretic medicine
• Calcium-based antacids

Struvite stones are more common in women. It is more common in those with past UTIs.

Uric acid stones are more common in those with:

• High amounts of red meat or poultry in diet
• Gout
• Rapid weight loss
• Chemotherapy

Symptoms

Most kidney stones will not cause symptoms. Other stones may cause:

• Sharp, stabbing pain in the mid-back
• Pain in the lower belly, groin, or genital areas
• Nausea and vomiting
• Blood in the urine
• Increased need to urinate
• Burning pain during urination
• Fever

Diagnosis

The doctor will ask about symptoms and past health. A physical exam will be done. Urine may be tested to look for infection or blood. The doctor may suspect a stone based on symptoms. Images of the urinary tract will show if a stone is present. Tests may include:

• X-ray
• Spiral CT scan
• Ultrasound
• Intravenous pyelogram (IVP)

Blood tests may also be done to look for a cause.

Treatment

The stones may pass in urine without problems. Drinking water can also help to flush small stones. Pain medicine may be needed.

Surgery may be needed if:

• Stones are very large or growing larger.
• There is bleeding, infection, or damage to the kidney.
• Urine flow is blocked.
• Stone cannot pass on its own.

Types of surgery include:

• Ureteroscopy—does not need cuts in the skin. A small tube is passed up into the tract to the stone. Tools are passed through this tube to remove the stone.
• Percutaneous nephrolithotomy—a small cut is made on the low back. A scope is passed through this cut. The stone can then be broken into pieces and removed.
• Lithotomy—a large incision will be used. This will give access to the area to remove stones. It is rarely used. The choices with small or no incisions are more common now.

A stent may be placed for a short time. The stent will help to keep the passage open to allow the stone to pass. It will help if there is too much swelling in the path that the stone has to pass through.

Extracorporeal Shock Wave Lithotripsy (ESWL) uses shockwaves through the skin to help break up the stone. A machine delivers the shockwave while you lie on a table. The waves break up large stones. The smaller pieces should be able to pass through the urine.

Prevention

Once you have had a kidney stone, you are more likely to have another. To help reduce the chance of another kidney stone:

• Drink plenty of fluids, especially water.
• Talk to your doctor about what diet is right for you. You may have to avoid certain food or drinks.
• Medicine may help to stop some stones from forming again.