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 are a common but painful urinary-tract disorder; men are more likely than women to get them. Kidney stones can cause severe pain, but usually do not cause any permanent damage to the urinary tract or body.
Causes of Kidney Stones
Kidney stones can form when substances in the urine such as calcium, oxalate and phosphorus become highly concentrated. Although the exact cause of kidney stones cannot always be determined, people with the following are at increased risk:
- Family history of kidney stones
- Chronic diarrhea
- Crohn's disease
- High level of calcium in the urine
Because their urine is more concentrated, people who do not drink enough fluids may be at higher risk for developing kidney stones. Taking certain medications can also increase their risk.
Symptoms of Kidney Stones
Most kidney stones cause terrible pain as they move through the urinary tract and into the ureter. Types of pain and other common symptoms include the following:
- Severe pain in the lower side and back
- Pain radiating to the abdomen and groin
- Bloody or cloudy urine
- Frequent and painful urination
Pain caused by a kidney stone may increase in intensity as the stone moves through the urinary tract.
Diagnosis of Kidney Stones
Kidney stones are diagnosed through a physical examination and a review of symptoms. Diagnostic tests include the following:
- Blood tests
- Urine tests
- Intravenous pyelogram (IVP)
- CT scan
Sometimes, even before they cause symptoms, kidney stones be identified on X-rays, which can show the location of stones in the kidney or urinary tract.
Treatment of Kidney Stones
Treatment is not usually necessary for small kidney stones; most pass on their own after drinking plenty of water. Pain medication may be prescribed to relieve symptoms. A larger stone that cannot pass on its own, or that blocks the urinary tract, may require more aggressive treatment, which is designed to locate the stone, and break it up into tiny pieces so it can pass through the urine. This may be performed through a procedure known as a shock wave lithotripsy (SWL), or a ureteroscopy. More-invasive surgery may be necessary to remove a very large stone.
Prevention of Kidney Stones
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 fat intake
- Eating a low-salt diet
Medication that helps to control levels of minerals and acid in urine of people who are prone to developing kidney stones may also be prescribed. People who have had previous kidney stones are at risk for having them recur, although implementing the preceding lifestyle changes may help to reduce that risk.