Stone Disease

What Are Kidney Stones?

Kidney stones are crystallike structures formed in the various parts of the urinary tract (Figure 1). Stones start small and gradually grow larger. Stone formation, shape, and growth are dependent on the total amount and types of crystals and all chemicals in the urine. It is believed that growth can be speeded by chemicals in the urine called "promoters" or slowed or stopped by other chemicals ("inhibitors").

Stones nearly always form in the kidney, where they may remain without symptoms and do not require treatment. However, they may cause obstruction or break loose and try to pass with the normal flow of urine through the urinary tract. More commonly, a stone will enlarge or move and cause pain and obstruction. The pain of trying to pass a kidney stone has been described as the most severe pain in the back, side, or abdomen that a person may experience. The pain may be steady or come in waves and may be associated with nausea, vomiting, and blood in the urine. An acute attack is a true medical emergency because of the severe symptoms.

How Common Are Kidney Stones?

Approximately one person in 200 will form a kidney stone this year, which will total more than 1 million cases in the United States. In these cases, approximately 80% of the stones will pass spontaneously, while the remaining 20% will need treatment. If a person forms a kidney stone, there is a 50% chance of another stone forming in 5-10 years without treatment.

The cause of kidney stone can be determined in 75% of cases by a metabolic evaluation. This evaluation analyzes the stone, blood, and urine chemistry of the patient. If an abnormality is found, the recurrence rate can be reduced with treatment from 50% to 10%. Some of the more common causes of stones are low fluid intake and malfunctions in the way the body absorbs, manufactures, or eliminates urinary products that can form crystals.

Can Kidney Stones Be Prevented?

There are many risk factors leading to the formation of kidney stones. Some of these include a family history of stones, certain variations in kidney anatomy, and the amount of fluid consumed during the day. Some stones are caused by genetic conditions or other medical conditions such as gout, eating disorders, or intestinal disease.

How Are Kidney Stones Diagnosed?

A kidney stone "attack" can often be determined by the location and pattern of pain, along with the associated symptoms of nausea, vomiting, and blood in the urine. Special tests are needed to determine the stone size and location. These tests usually include x-rays of the abdomen and an intravenous pyelogram (IVP), in which a fluid is injected into a vein to show the anatomy and drainage of the urinary tract. Other tests such as ultrasound or CAT scan can be used. Specialized blood and urine tests may be used to check for infection and chemical problems that may occur in kidney stone disease.

How Do I Get Rid of My Kidney Stones?

Not all kidney stones require treatment. Stones that are causing no symptoms, no obstruction, and are not at risk for damaging the urinary tract may be candidates for observation. About 80% of kidney stones will pass spontaneously through your urinary tract when you urinate without medical help. These stones, however, may cause severe symptoms until spontaneous passage occurs.

If a stone needs treatment because it is too large to pass, lithotripsy is usually recommended. Lithotripsy is the break up (tripsy) of a stone (litho). Various types of energy may be used to break up a stone into small enough particles to be removed or pass. These energies include shock waves (delivered without surgery by a machine) and energies delivered directly to the stone by ultrasound, laser fiber, mechanical impactor, or electricity.

Energy delivered directly to the stone must be passed through an instrument (endoscope) inserted into the urinary tract. This is commonly referred to as endoscopic management.

What Are the Treatment Methods?

If a stone needs treatment, the goal of treatment is to completely remove the stone that has been diagnosed and is causing symptoms. Treatment methods usually are chosen based on the location of the stone:

Kidney stones:

• Shock wave lithotripsy: a noninvasive method using energy to fragment stones (Figure 2)
• Percutaneous (through the skin) lithotripsy: an endoscope is inserted into the kidney with energy applied directly to the stone
• Open surgery with an incision

Ureteral stones

• Shock wave lithotripsy
• Endoscopic lithotripsy
• Endoscopic removal
• Open surgery

Bladder stones

• Endoscopic extraction or lithotripsy
• Open surgery

What Kind Treatment is Best for Me?

All of the treatments have advantages and disadvantages. Generally, the more complicated and more invasive treatments have a higher success rate. Sometimes a combination of treatments is necessary for the best outcome. A decision as to which treatment should be used depends on many factors. The stone size, location, composition, and hardness are important as well as the individual anatomy of the urinary tract, the medical history, and health of the patient. The different treatments may have different requirements. Some treatments or equipment are mobile and not available at all times at all treatment sites.

All of these factors must be considered in choosing the most appropriate treatment for a kidney stone. As the patient, your responsibility is to participate in the decision and choice of therapy. Your right is to insist upon clear and complete discussions with your doctor as to the advantages and disadvantages of each therapy. Only through open communication and being well informed can you and your doctor make the best choice.

What Happens After I Have Been Treated for a Kidney Stone?

If a treatable problem is found, you then have the responsibility of following your doctor's recommendations. Common treatments include diet changes, adjustment in fluid intake, and the use of medication. Often a combination of treatments is recommended. If the treatment program is followed, better health and fewer stones will result.

Developed by Noel E. Sankey, MD and Martin I. Resnick, MD, and provided by Bayer, Pharmaceutical Division.

The information provided in this section should in no way serve as medical advice. Readers are encouraged to confirm the information contained here with other sources and seek medical advice from a physician. Neither the authors nor any other party who has been involved in the preparation or publication of this work warrants that the information contained herein is in every respect accurate or complete and they are not responsible for any errors or omissions or for the results obtained for the use of such information.

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