Kidney Stones: Symptoms, Causes, and Treatment

Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: Barbara K. Hecht, PhD

One in every 20 people develop a kidney stone at some point in their life. Kidney stones, known medically as renal calculi, form within the kidney itself or in other parts of the urinary tract. The condition of having kidney stones is termed nephrolithiasis or urolithiasis.

Kidney stones may produce severe symptoms. People who have kidney stones report the sudden onset of excruciating cramping pain in their side, groin, or abdomen. Changes in body position do not relieve this pain. It may be so severe that it is accompanied by nausea and vomiting. Kidney stones also characteristically cause blood in the urine. If infection is present in the urinary tract along with the stones, there may be fever and chills.

Kidney stones form when there is a decrease in urine volume or an excess of stone-forming substances in the urine. The most common type of kidney stone contains calcium in combination with either oxalate or phosphate. Other chemical compounds that can form stones in the urinary tract include uric acid and the amino acid cystine.

Dehydration through reduced fluid intake or strenuous exercise without adequate fluid replacement increases the risk of kidney stones. Obstruction to the flow of urine can also lead to stone formation. Kidney stones associated with infection in the urinary tract are known as struvite or infection stones.

Men are especially likely to develop kidney stones, and whites get them more often than African Americans. The prevalence of kidney stones begins to rise when men reach their 40s and continues to climb into their 70s. People who have already had more than one kidney stone are prone to develop more stones.

A number of different medical conditions can increase the risk of developing lead to kidney stones:

  • Gout results in an increased amount of uric acid in the urine and can lead to the formation of uric acid stones.

  • Hypercalciuria (high calcium in the urine), another inherited condition, causes stones in more than half of cases. In this condition, too much calcium is absorbed from food and excreted into the urine, where it may form calcium phosphate or calcium oxalate stones.

  • Other conditions associated with an increased risk of kidney stones include hyperparathyroidism, kidney diseases such as renal tubular acidosis, and some inherited metabolic conditions, including cystinuria and hyperoxaluria.

  • People with inflammatory bowel disease or those who have had an intestinal bypass or ostomy surgery are also more likely to develop kidney stones.

  • Some medications also raise the risk of kidney stones. These medications include some diuretics, calcium-containing antacids, and the protease inhibitor indinavir (Crixivan), a drug used to treat HIV infection.

Most kidney stones eventually pass through the urinary tract on their own with ample fluid intake. Pain medications can be prescribed for symptom relief. For kidney stones which do not pass on their own, a procedure called lithotripsy is often used. In this procedure, shock waves are used to break up a large stone into smaller pieces that can pass through the urinary system.

Surgical techniques have also been developed to remove kidney stones. This may be done through a small incision in the skin (percutaneous nephrolithotomy) or through an instrument known as an ureteroscope passed through the urethra and bladder up into the ureter.

Rather than having to undergo treatment, it is best to avoid kidney stones in the first place. Drinking adequate water can help reduce the risk of kidney stones. (The National Institutes of Health recommend drinking up to 12 full glasses of water a day if you've already had a kidney stone.) Water helps to flush away the substances that form stones in the kidneys.

Last Editorial Review: 7/1/2008