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Kidney stones

A common affliction

Kidney stones are among the most painful and prevalent of urologic disorders. More than a million kidney stone cases are diagnosed each year, with an estimated 10 percent of Americans destined to suffer from it at some point in their lives.
Fortunately, most stones pass out of the body without any intervention. If you are not so lucky, the following information should help you and your doctor address the causes, symptoms and possible complications created by your kidney stone disease.

Normal Conditions

The urinary tract, or system, consists of the kidneys, ureters, bladder and urethra. The kidneys are two bean-shaped organs below the ribs in the back of the torso. They are responsible for maintaining balance by removing extra water and wastes from the blood and converting it to urine. The kidneys keep a stable balance of salts and other substances in the blood. They also produce hormones that build strong bones and help form red blood cells. Urine is carried by narrow muscular tubes, the ureters, from the kidneys to the bladder, a triangular-shaped reservoir in the lower abdomen. Like a balloon, the bladder's walls stretch and expand to store urine and then flatten when urine is emptied through the urethra to outside the body.

What is a Kidney Stone?

A stone forms in the kidney when there is an imbalance between certain urinary components - chemicals such as calcium, oxalate and phosphate - that promote crystallization and others that inhibit it. Most stones contain calcium in combination with oxalate and/or phosphate.
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. Much less common are pure uric acid stones. Much rarer are hereditary stones called cystine stones. Even more rare are those linked to hereditary disorders.

Who Gets Kidney Stones?

For unknown reasons, the number of people in the United States with kidney stones has been increasing over the past 20 years. Caucasians are more prone to develop kidney stones than African Americans. Although stones occur more frequently in men, the number of women who get them has been increasing over the past 10 years. Kidney stones strike most typically between the ages of 20 and 40. If a person forms a stone, there is a 50 percent chance they will develop another stone.

What Causes a Stone to Form?

Scientists do not always know what makes stones form. While certain foods may promote stones in susceptible people, researchers do not believe that eating a specific item will cause stones in people who are not vulnerable. Yet they are confident that factors - such as a family or personal history of kidney stones and other urinary infections or diseases - have a definite connection to this problem. Climate and water intake may also play a role in stone formation.
Stones can also form because of obstruction to the urinary passage, like in prostate enlargement or stricture disease. Stone formation has also been linked to hyperparathyroidism, an endocrine disorder that results in more calcium in your urine. Susceptibility can also be raised if you are among the 70 percent of people with rare hereditary disorders. such as cystinuria or primary hyperoxaluria, who develop kidney stones because of excesses of the amino acid, cystine or the oxalate in your urine.

Another condition that can cause stones to form is absorptive hypercalciuria, a surplus of calcium in the urine that occurs when the body absorbs too much from food. Similarly, hyperuricosuria, excess uric acid tied to gout or the excessive consumption of meat products, may also trigger kidney stones.
Consumption of calcium pills by a person who is at risk to form stones, certain diuretics or calcium-based antacids may increase the risk of forming stones by increasing the amount of calcium in the urine. Calcium oxalate stones may also form in people who have chronic inflammation of the bowel or who have had an intestinal bypass operation or ostomy.

What Are the Symptoms?

Usually, the symptom of a kidney stone is extreme pain that has been described as being worse than child labor pains. The pain often begins suddenly as the stone moves in the urinary tract, causing irritation and blockage. Typically, a person feels a sharp, cramping pain in the back or in the lower abdomen, which may spread to the groin. Sometimes a person will complain of blood in the urine, nausea and/or vomiting.
Occasionally, stones do not produce any symptoms. But while they may be silent, they can be growing, even threatening irreversible damage to kidney function. More commonly, however, if a stone is not large enough to prompt major symptoms, it still can trigger a dull ache that is often confused with muscle or intestinal pain.

If the stone is too large to pass easily, pain continues as the muscles in the wall of the tiny ureter try to squeeze the stone along into the bladder. One may feel the need to urinate more often or feel a burning sensation during urination. In a man, pain may move down to the tip of the penis. If the stone is close to the lower end of the ureter, a person will frequently feel like they have not fully completed urination.
If fever or chills accompany any of these symptoms, there may be an infection. Contact your urologist immediately.

How Are Stones Diagnosed?

Sometimes silent stones are found on X-rays taken during a general health examination. These stones would likely pass unnoticed. If they are large, then treatment should be offered. More often, kidney stones are found on an X-ray or sonogram taken on someone who complains of blood in the urine or sudden pain. Blood and urine tests also help detect any abnormal substance that might promote stone formation.
If your doctor suspects a stone but is unable to make a diagnosis from an X-ray, he/she may scan the urinary system with intravenous pyelography (IVP). It is an imaging technique that utilizes radiopaque injections of dye, followed by abdominal X-rays.

Since this technique requires prep, it has been replaced in many hospitals by an abdominal/pelvic CT scan, an extremely accurate diagnostic tool that can detect almost all types of kidney stones painlessly.

How Are They Treated?

Treating kidney stone disease depends largely on the size, position and number of stones in your system. Luckily, the majority of small stones that are not causing infection, blockage or symptoms will pass if you simply drink plenty of fluids each day. Consuming two to three quarts of water increases urine production, which eventually washes kidney or other stones out of the system. Once they have passed, no other treatment is necessary. The doctor usually asks one to save the passed stone(s) for testing.
Also, renal colic, the sudden flank pain that occurs when small stones start down the ureter, can usually be treated with bed rest and analgesics or painkillers. Certain types of stones, such as those made or uric acid, can be broken up with medical therapy. The majority, however, are composed of calcium and are not responsive to medicine.
Surgery should be reserved as an option for cases where other approaches have failed or should not be tried.

Until recently, surgery to remove a stone was very painful and required a lengthy recovery time (four to six weeks). Today, treatment for these stones is greatly improved and many options do not require major surgery.
Extracorporeal shock wave lithotripsy is the most frequently used procedure for eliminating kidney stones. It works by directing ultrasonic waves at the dense kidney stones. The stones break down into sand-like particles and are easily passed through the urinary tract in the urine.
Percutaneous nephrolithotomy is the treatment of choice for patients with larger kidney stones.

In this procedure, the surgeon makes a tiny cut in the flank area and then uses an instrument called a nephroscope to locate and remove the stone. For larger stones, a type of energy probe may be needed to break the stone into small pieces.
Ureteroscopy involves the use of ureteroscopes, small flexible or semi-rigid telescopes that can be inserted up the urethra and allow the doctor to view a ureteral stone directly. They also have small working channels through which various devices can be passed to remove or fragment the stone.

What Can Be Expected After Treatment?

Although stone recurrence rates differ with individuals, in general you have a 50 percent chance of redeveloping stones within the next five years. So prevention is essential. Your urologist may follow up with several tests to determine which factors - medication or diet - should be changed to reduce your further risk.

Information provided by, a patient education site written and reviewed in partnership with the American Urological Association Foundation