What is Kidney stones
A kidney stone is a hard mass developed from crystals that separate from the urine within the urinary tract. Normally, urine contains chemicals that prevent or inhibit the crystals from forming. These inhibitors do not seem to work for everyone, however, so some people form stones. If the crystals remain tiny enough, they will travel through the urinary tract and pass out of the body in the urine without being noticed.

Kidney stones may contain various combinations of chemicals. The most common type of stone contains calcium in combination with either oxalate or phosphate. These chemicals are part of a person’s normal diet and make up important parts of the body, such as bones and muscles.

A less common type of stone is caused by infection in the urinary tract. This type of stone is called a struvite or infection stone. Another type of stone, uric acid stones, are a bit less common, and cystine stones are rare.

Urolithiasis is the medical term used to describe stones occurring in the urinary tract. Other frequently used terms are urinary tract stone disease and nephrolithiasis. Doctors also use terms that describe the location of the stone in the urinary tract. For example, a ureteral stone—or ureterolithiasis—is a kidney stone found in the ureter. To keep things simple, the general term kidney stones is used throughout this fact sheet.

Gallstones and kidney stones are not related. They form in different areas of the body. Someone with a gallstone is not necessarily more likely to develop kidney stones.

What are the symptoms of kidney stones?
Kidney stones often do not cause any symptoms. Usually, the first symptom of a kidney stone is extreme pain, which begins suddenly when a stone moves in the urinary tract and blocks the flow of urine. Typically, a person feels a sharp, cramping pain in the back and side in the area of the kidney or in the lower abdomen. Sometimes nausea and vomiting occur. Later, pain may spread to the groin.

If the stone is too large to pass easily, pain continues as the muscles in the wall of the narrow ureter try to squeeze the stone into the bladder. As the stone moves and the body tries to push it out, blood may appear in the urine, making the urine pink. As the stone moves down the ureter, closer to the bladder, a person may feel the need to urinate more often or feel a burning sensation during urination.

If fever and chills accompany any of these symptoms, an infection may be present. In this case, a person should contact a doctor immediately.

How are kidney stones treated?

Fortunately, surgery is not usually necessary. Most kidney stones can pass through the urinary system with plenty of water—2 to 3 quarts a day—to help move the stone along. Often, the patient can stay home during this process, drinking fluids and taking pain medication as needed. The doctor usually asks the patient to save the passed stone(s) for testing. It can be caught in a cup or tea strainer used only for this purpose.

Lifestyle Changes
A simple and most important lifestyle change to prevent stones is to drink more liquids—water is best. Someone who tends to form stones should try to drink enough liquids throughout the day to produce at least 2 quarts of urine in every 24-hour period.

In the past, people who form calcium stones were told to avoid dairy products and other foods with high calcium content. Recent studies have shown that foods high in calcium, including dairy products, may help prevent calcium stones. Taking calcium in pill form, however, may increase the risk of developing stones.

Patients may be told to avoid food with added vitamin D and certain types of antacids that have a calcium base. Someone who has highly acidic urine may need to eat less meat, fish, and poultry. These foods increase the amount of acid in the urine.

To prevent cystine stones, a person should drink enough water each day to dilute the concentration of cystine that escapes into the urine, which may be difficult. More than a gallon of water may be needed every 24 hours, and a third of that must be drunk during the night.

Surgical Treatment

Surgery may be needed to remove a kidney stone if it

• does not pass after a reasonable period of time and causes constant pain

•  is too large to pass on its own or is caught in a difficult place

• blocks the flow of urine

• causes an ongoing urinary tract infection

• damages kidney tissue or causes constant bleeding

• has grown larger, as seen on follow-up x rays

Until 20 years ago, open surgery was necessary to remove a stone. The surgery required a recovery time of 4 to 6 weeks. Today, treatment for these stones is greatly improved, and many options do not require major open surgery and can be performed in an outpatient setting.