Kidney Stones

A kidney stone, also known as renal calculi or nephrolithiasis, is a hardened mass of mineral and acid salts that separates from the urine and travels through the urinary tract. The urine normally dilutes and dissolves these substances, but when the composition of urine is unbalanced, crystallized stones can form. Kidney stones can cause severe pain and occasionally can lead to permanent damage to the urinary tract or body.

Causes of Kidney Stones

Kidney stones can form when substances such as calcium, oxalate and phosphorus become highly concentrated in the urine. Although the exact cause of kidney stones cannot always be determined, people with the following are at increased risk:

  • Family history of kidney stones
  • Gout
  • Chronic diarrhea
  • Crohn's disease
  • Obesity
  • High level of calcium in the urine
  • Certain medications

Symptoms of Kidney Stones

Kidney stones often do not cause any symptoms and are detected by accident on imaging studies.  Patients with symptoms may have any of the following:

  • Severe pain in the flank and back
  • Pain radiating to the abdomen and groin
  • Bloody or cloudy urine
  • Frequent and painful urination
  • Nausea
  • Fever

Diagnosis of Kidney Stones

Kidney stones are diagnosed through a review of systems and physical examination. Diagnostic tests may include the following:

  • Blood tests
  • Urine tests
  • CT scan
  • Ultrasound
  • Xrays

Treatment of Kidney Stones

Surgical treatment is not usually necessary for small kidney stones, and many will pass on their own after drinking plenty of water. Pain medication may be prescribed to relieve symptoms in these cases.

A larger stone that cannot pass on its own, or that blocks the urinary tract, may require surgical removal of the stone or lithotripsy.  Lithotripsy uses sound waves to break the stone into smaller pieces that can pass on their own.

Prevention of Kidney Stones

Patients who have had at least kidney stones are at high risk for developing another stone in the future.  Although not all kidney stones can be prevented, certain lifestyle changes, including the following, may help to reduce the risk of developing them:

  • Drinking plenty of fluids
  • Reducing saturated fat and red meat intake
  • Eating a low-salt diet

Medications also may be prescribed to control levels of acid and certain minerals in the urine.

Additional Resources