Kidney Stones

Kidney stones are formed by a complex process of crystal formation and deposition within the kidney, ureter, or bladder. People with kidney stones most often present because of severe pain or blood in the urine. About 5 percent of women and 12 percent of men will have at least one episode of kidney stones by the age of 70. Kidney stones are more prevalent in obese patients, particularly men and those who have abdominal obesity (higher waist circumferences). The mechanism linking obesity to a greater prevalence of kidney stones is not yet known.”

There are three types of stones: calcium, struvite, and cystine. The most common type is calcium with oxalate or phosphate. These can be caused by high calcium levels in the blood, genetic factors, intestinal bypass surgery, or diets rich in oxalate. Struvite stones are caused by chronic urinary tract infections with certain bacteria. Uric acid stones tend to develop in people with high blood levels from gout or chemotherapy, or people eating high-protein diets causing acidic urine. Cystine stones occur rarely in association with hereditary disorders.

In some people, kidney stones pass through the urinary tract without causing symptoms. However, stones can also cause obstruction of the kidney or ureter. This causes severe episodic pain that usually begins in the back and moves to the groin and is associated with nausea, vomiting, and blood in the urine. Physicians can diagnose kidney stones based on urine tests, X-rays, computerized tomography (CT) scans, or ultrasounds.

Most kidney stones eventually pass on their own with two to three quarts of fluid intake a day. Treatment with a calcium channel blocker, a type of blood pressure medicine that relaxes smooth muscle like that in the ureter, may speed up the process. Stones that need to be removed urgently are very large or fail to pass on their own may require additional intervention, such as uretroscopy or extracorporeal shock wave lithotripsy.

Kidney stones frequently recur but can be prevented. The single most important lifestyle change is to drink up to a gallon of water a day. People with calcium stones should restrict foods rich in oxalate such as beets, chocolate, coffee, cola, nuts, rhubarb, spinach, strawberries, tea, and wheat bran. Reduction of dietary salt and animal protein also helps. As a rule, restricting calcium is not recommended because calcium in normal amounts combines with oxalate in the gastrointestinal tract and prevents its absorption. When calcium is low, oxalate is absorbed, which leads to more stone formation. Less commonly, specific medications can correct the underlying problem resulting in stones.