Kidney stones, one of the most painful of the urologic disorders, are not a product of modern
life. Scientists have found evidence of kidney stones in a 7,000-year-old Egyptian mummy.
Unfortunately, kidney stones are one of the most common disorders of the urinary tract. In
2000, patients made 2.7 million visits to health care providers and more than 600,000
patients went to emergency rooms for kidney stone problems. Men tend to be affected more
frequently than women. [S1]

Most kidney stones pass out of the body without any intervention by a physician. Stones that
cause lasting symptoms or other complications may be treated by various techniques, most
of which do not involve major surgery. Also, research advances have led to a better
understanding of the many factors that promote stone formation.

About 5% of American women and 12% of men will develop a kidney stone at some time in
their life, and prevalence has been rising in both sexes. Approximately 80% of kidney stones
are composed of calcium oxalate and calcium phosphate, 10% of struvite (magnesium
ammonium phosphate produced during infection with bacteria that possess the enzyme
urease), 9% of uric acid; and the remaining 1% are composed of cystine or ammonium acid
urate or are diagnosed as drug-related stones. Kidney stones ultimately arise because of an
unwanted phase change of these substances from liquid to solid state. [1]

Kidneys are bean-shaped organs, each about the size of a fist. They are located near the
middle of the back, just below the rib cage. The kidneys are sophisticated trash collectors.
Every day, kidneys process about 200 quarts of blood to sift out about 2 quarts of waste
products and extra water. The waste and extra water become urine, which flows to the
bladder through tubes called ureters. Bladder stores urine until urination.
The wastes in the blood come from the normal breakdown of active muscle and from the
food you eat. Your body uses the food for energy and self-repair. After your body has taken
what it needs from the food, waste is sent to the blood. If your kidneys did not remove these
wastes, the wastes would build up in the blood and damage your body. The kidneys remove
extra water and wastes from the blood, converting it to urine. They also keep a stable
balance of salts and other substances in the blood. The kidneys produce hormones that help
build strong bones and help form red blood cells. [S1, S2]

What is a kidney stone?
A kidney stone is a hard mass developed from crystals that separate from the urine and build
up on the inner surfaces of the kidney. 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. There are four major types of
kidney stones (1) CALCIUM STONE 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. (2) STRUVITE
STONE struvite stone A struvite stone may form after an infection in the urinary system.
These stones contain the mineral magnesium and the waste product ammonia. (3) URIC
ACID STONE A uric acid stone may form when there is too much acid in the urine. If you tend
to form uric acid stones, you may need to cut back on the amount of meat you eat. (4)
CYSTINE STONE Cystine stones are rare. Cystine is one of the building blocks that make up
muscles, nerves, and other parts of the body. Cystine can build up in the urine to form a
stone. The disease that causes cystine stones runs in families. Kidney stones may be as
small as a grain of sand or as large as a pearl. Some stones are even as big as golf balls.
Stones may be smooth or jagged. They are usually yellow or brown. [S2]

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, however, the
term "kidney stones" is used throughout this fact sheet.

Gallstones and kidney stones are not related. They form in different areas of the body. If you
have a gallstone, you are not necessarily more likely to develop kidney stones.

Who gets kidney stones?
For unknown reasons, the number of people in the United States with kidney stones has
been increasing over the past 30 years. The prevalence of stone-forming disease rose from
3.8 percent in the late 1970s to 5.2 percent in the late 1980s and early 1990s. White
Americans are more prone to develop kidney stones than African Americans. Stones occur
more frequently in men. The prevalence of kidney stones rises dramatically as men enter
their 40s and continues to rise into their 70s. For women, the prevalence of kidney stones
peaks in their 50s. Once a person gets more than one stone, others are likely to develop. [S1]

What causes kidney stones?
Certain foods may promote stone formation in people who are susceptible. A person with a
family history of kidney stones may be more likely to develop stones. Urinary tract infections,
kidney disorders such as cystic kidney diseases, and certain metabolic disorders such as
hyperparathyroidism are also linked to stone formation. In addition, more than 70 percent of
people with a rare hereditary disease called renal tubular acidosis develop kidney stones.
Cystinuria and hyperoxaluria are two other rare, inherited metabolic disorders that often
cause kidney stones. In cystinuria, too much of the amino acid cystine, which does not
dissolve in urine, is voided. This can lead to the formation of stones made of cystine. In
patients with hyperoxaluria, the body produces too much of the salt oxalate. When there is
more oxalate than can be dissolved in the urine, the crystals settle out and form stones.
Hypercalciuria is inherited. It is the cause of stones in more than half of patients. Calcium is
absorbed from food in excess and is lost into the urine. This high level of calcium in the urine
causes crystals of calcium oxalate or calcium phosphate to form in the kidneys or urinary

Other causes of kidney stones are hyperuricosuria which is a disorder of uric acid
metabolism, gout, excess intake of vitamin D, urinary tract infections, and blockage of the
urinary tract. Certain diuretics which are commonly called water pills or calcium-based
antacids may increase the risk of forming kidney stones by increasing the amount of calcium
in the urine.

Calcium oxalate stones may also form in people who have a chronic inflammation of the
bowel or who have had an intestinal bypass operation, or ostomy surgery. As mentioned
above, struvite stones can form in people who have had a urinary tract infection. People who
take the protease inhibitor indinavir, a drug used to treat HIV infection, are at risk of
developing kidney stones.

What are the symptoms?
Kidney stones often do not cause any symptoms. Usually, the first symptom of a kidney stone
is extreme pain, which occurs when a stone acutely blocks the flow of urine. The pain often
begins suddenly when a stone moves in the urinary tract, causing irritation or blockage.
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 tiny
ureter try to squeeze the stone along into the bladder. As a stone grows or moves, blood may
appear in the urine. As the stone moves down the ureter closer to the bladder, you may feel
the need to urinate more often or feel a burning sensation during urination.

In sum, most kidney stones pass out of the body without help from a doctor. But sometimes a
stone will not just go away. It may even get larger. You should call a doctor when you have any
one of the following signs and symptoms: (1) extreme pain in your back or side, (2) blood in
urine, (3) fever and chills, (4) vomiting, (5) urine that smells bad or looks cloudy and (6) a
burning feeling when you urinate.

How are kidney stones diagnosed?
Sometimes "silent" stones—those that do not cause symptoms—are found on x rays
taken during a general health exam. If they are small, these stones would likely pass out of
the body unnoticed.

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. These diagnostic images give the doctor
valuable information about the stone's size and location. Blood and urine tests help detect
any abnormal substance that might promote stone formation.

The doctor may decide to scan the urinary system using a special test called a CT
(computed tomography) scan or an IVP (intravenous pyelogram). The results of all these
tests help determine the proper treatment.

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,
you can stay home during this process, drinking fluids and taking pain medication as
needed. The doctor usually asks you to save the passed stone(s) for testing. (You can catch
it in a cup or tea strainer used only for this purpose.)

The First Step: Prevention
What can I do to avoid more stones?
Drink more water. Try to drink 12 full glasses of water a day. Drinking lots of water helps to
flush away the substances that form stones in the kidneys.

You can also drink ginger ale, lemon-lime sodas, and fruit juices. But water is best. Limit your
coffee, tea, and cola to one or two cups a day because the caffeine may cause you to lose
fluid too quickly.

Your doctor may ask you to eat more of some foods and to cut back on other foods. For
example, if you have a uric acid stone, your doctor may ask you to eat less meat, because
meat breaks down to make uric acid.

The doctor may give you medicines to prevent calcium and uric acid stones.
If you've had more than one kidney stone, you are likely to form another; so prevention is very
important. To prevent stones from forming, your doctor must determine their cause. He or
she will order laboratory tests, including urine and blood tests. Your doctor will also ask about
your medical history, occupation, and eating habits. If a stone has been removed, or if you've
passed a stone and saved it, the laboratory should analyze it because its composition helps
in planning treatment.

You may be asked to collect your urine for 24 hours after a stone has passed or been
removed. The sample is used to measure urine volume and levels of acidity, calcium,
sodium, uric acid, oxalate, citrate, and creatinine (a product of muscle metabolism). Your
doctor will use this information to determine the cause of the stone. A second 24-hour urine
collection may be needed to determine whether the prescribed treatment is working.
Lifestyle Changes

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

People who form calcium stones used to be told to avoid dairy products and other foods with
high calcium content. But 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.

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

To prevent cystine stones, you 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.
Foods and Drinks Containing Oxalate

People prone to forming calcium oxalate stones may be asked by their doctor to cut back on
certain foods if their urine contains an excess of oxalate: beets, chocolate, coffee, cola, nuts,
rhubarb, spinach, strawberries, tea and wheat bran.

People should not give up or avoid eating these foods without talking to their doctor first. In
most cases, these foods can be eaten in limited amounts.
Medical Therapy

The doctor may prescribe certain medications to prevent calcium and uric acid stones.
These drugs control the amount of acid or alkali in the urine, key factors in crystal formation.
The drug allopurinol may also be useful in some cases of hyperuricosuria.
Doctors usually try to control hypercalciuria, and thus prevent calcium stones, by prescribing
certain diuretics, such as hydrochlorothiazide. These drugs decrease the amount of calcium
released by the kidneys into the urine by favoring calcium retention in bone. They work best
when sodium intake is low.

Very rarely, patients with hypercalciuria may be given the drug sodium cellulose phosphate,
which binds calcium in the intestines and prevents it from leaking into the urine.
If cystine stones cannot be controlled by drinking more fluids, your doctor may prescribe
drugs such as Thiola and Cuprimine, which help reduce the amount of cystine in the urine.
For struvite stones that have been totally removed, the first line of prevention is to keep the
urine free of bacteria that can cause infection. Your urine will be tested regularly to be sure
that no bacteria are present.

If struvite stones cannot be removed, your doctor may prescribe a drug called
acetohydroxamic acid (AHA). AHA is used with long-term antibiotic drugs to prevent the
infection that leads to stone growth.

People with hyperparathyroidism sometimes develop calcium stones. Treatment in these
cases is usually surgery to remove the parathyroid glands (located in the neck). In most
cases, only one of the glands is enlarged. Removing the glands cures the patient's problem
with hyperparathyroidism and with kidney stones as well.

Surgical Treatment
Surgery should be reserved as an option for cases where other approaches have failed.
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 ongoing urinary tract infection
· damages kidney tissue or causes constant bleeding
· has grown larger (as seen on followup x ray studies).
Until 20 years ago, surgery was necessary to remove a stone. It was very painful and
required a recovery time of 4 to 6 weeks. Today, treatment for these stones is greatly
improved, and many options do not require major surgery.

Shock Waves-Extracorporeal Shockwave Lithotripsy
Your doctor can use a machine to send shock waves directly to the kidney stone. The shock
waves break a large stone into small stones that will pass through your urinary system with
your urine.

Two types of shock wave machines exist. With one machine, you sit in a tub of water. With
the other type of machine, you lie on a table.

The full name for this method is extracorporeal shockwave lithotripsy. Doctors often call it
ESWL for short. Lithotripsy is a Greek word that means stone crushing.
Extracorporeal shockwave lithotripsy (ESWL) is the most frequently used procedure for the
treatment of kidney stones. In ESWL, shock waves that are created outside the body travel
through the skin and body tissues until they hit the denser stones. The stones break down into
sand-like particles and are easily passed through the urinary tract in the urine.

There are several types of ESWL devices. In one device, the patient reclines in a water bath
while the shock waves are transmitted. Other devices have a soft cushion on which the
patient lies. Most devices use either x rays or ultrasound to help the surgeon pinpoint the
stone during treatment. For most types of ESWL procedures, anesthesia is needed.
In most cases, ESWL may be done on an outpatient basis. Recovery time is short, and most
people can resume normal activities in a few days.

Complications may occur with ESWL. Most patients have blood in their urine for a few days
after treatment. Bruising and minor discomfort in the back or abdomen from the shock waves
are also common. To reduce the risk of complications, doctors usually tell patients to avoid
taking aspirin and other drugs that affect blood clotting for several weeks before treatment.
Another complication may occur if the shattered stone particles cause discomfort as they
pass through the urinary tract. In some cases, the doctor will insert a small tube called a stent
through the bladder into the ureter to help the fragments pass. Sometimes the stone is not
completely shattered with one treatment, and additional treatments may be needed. ESWL
is not ideal for very large stones.

Tunnel Surgery (Percutaneous Nephrolithotomy)
Sometimes a procedure called percutaneous nephrolithotomy is recommended to remove a
stone. This treatment is often used when the stone is quite large or in a location that does not
allow effective use of ESWL.

In this procedure, the surgeon makes a tiny incision in the back and creates a tunnel directly
into the kidney. Using an instrument called a nephroscope, the surgeon locates and removes
the stone. For large stones, some type of energy probe (ultrasonic or electrohydraulic) may
be needed to break the stone into small pieces. Generally, patients stay in the hospital for
several days and may have a small tube called a nephrostomy tube left in the kidney during
the healing process.

One advantage of percutaneous nephrolithotomy over ESWL is that the surgeon removes the
stone fragments instead of relying on their natural passage from the kidney.
Ureteroscope (Ureteroscopic Stone Removal)

A ureteroscope looks like a long wire. The doctor inserts it into the patient's urethra, passes
it up through the bladder, and directs it to the ureter where the stone is located. The
ureteroscope has a camera that allows the doctor to see the stone. A cage is used to catch
the stone and pull it out, or the doctor may destroy it with a device inserted through the


Up to 85% of all stone patients could anticipate lower risk of stone recurrence with
elementary reorientation of their lifestyle and dietary habits. Normalizing the major risk
factors is easy and cheap. About 15% of patients forming stones require additional specific
pharmacological prevention. The specific measures to avoid recurrence of the stone disease
are precisely defined. [8]


Renal stone formation has been explained by the physicochemical theory; i.e., nucleation,
growth and aggregation of crystals in the urine. Current medical prevention is based on this
theory and seeks to modulate promoters and inhibitors of stone formation. Recent studies
have identified increasing numbers of macromolecular inhibitors such as
glycosaminoglycans, bikunin, osteopontin and urinary prothrombin F1. These appear to be
more important than low-molecular inhibitors like citrate. [9]

Crystal retention in the nephron has been considered necessary for kidney stone formation;
researchers have found that calcium oxalate crystals can bind to renal epithelial cells. And,
oxalate and/or calcium oxalate crystals can damage renal epithelial cells and enhance crystal
binding. Concurrently, oxalate exposure induces genes coding macromolecular inhibitors,
which are supposed to be a protective mechanism against stone formationÂ…. [9]

Modern lifestyle, dietary habits and obesity emerge to be the promoters of idiopathic stone
disease. Cross-sectional studies showed significant correlations between these factors and
kidney stones with direct implications on our preventive concepts: normalization of body
mass index, adequate physical activity, balanced nutrition and sufficient circadian fluid
intake. Modern diets containing a lot of animal protein, refined carbohydrates and salt act on
the metabolism like an acid load. To overcome these disadvantageous effects, a sufficient
supply of potassium and alkali is required. Last but not least, calcium should not be
restricted. There is clear evidence from clinical and experimental research that a normal or a
high calcium supply is appropriate in calcium stone disease. Only in absorptive
hypercalciuria calcium restriction remains beneficial in combination with thiazide and citrate
therapy. [8]


L-ARGININE may benefit some people suffered from kidney stones; a study suggested.

Oral supplementation of l-arginine (l-arg) is suggested to be beneficial in many kidney
disorders [2]. Progasam V and co-workers from University of Madras, India, found intake of
ethylene glycol could increase urinary excretion of calcium and oxalate in rats, while l-arginine
supplementation could reduce the effect. In the study, citrate excretion was enhanced in the l-
arginine co-supplemented hyperoxaluric rats. In vitro study, l-arginine supplemented rat
Tamm-Horsfall glycoprotein showed inhibition in nucleation and aggregation phases,
whereas ethylene glycol-treated rat THP showed promotion of both calcium oxalate
nucleation and aggregation phases. They concluded that l-arginine could act as a potent
antilithic agent, by increasing the level of citrate in the hyperoxaluria-induced rats and
decreasing calcium oxalate binding to the THP. l-arginine also effectively prevents the
deposition of calcium oxalate crystals by curtailing the renal epithelial damage and protein
oxidation. [2]

Magnesium supplements may benefit people (with magnesium deficiency) suffered from
kidney stones, a few studies suggested.

Massey L from Washington State University evaluated the experimental evidence and clinical
trial outcomes as the basis for use of magnesium (Mg) supplements as therapy for calcium
oxalate nephrolithiasis. He concluded that magnesium inhibits calcium oxalate crystallization
in human urine and model systems. Magnesium also inhibits absorption of dietary oxalate
from the gut lumen. Three early trials of Mg oxide (MgO) and Mg hydroxide (Mg(OH)2)
reported lower rates of recurrent stone formation. However in a double-blind, randomized,
placebo-controlled trial with more carefully selected patients, there was no significant
difference between recurrence rates with 650 or 1300 mg MgO daily and the placebo.
Another trial reported 391 mg (21 meq) Mg daily as a mixed salt, Mg potassium citrate,
reduced calcium stone recurrence by 90%, similar to potassium citrate, but with better
gastrointestinal tolerance. The failure of MgO and Mg(OH)2 as sole therapy may be related
to poor absorption and low rates of Mg deficiency in the patient populations tested. [3]

Manipulation of gastrointestinal (GI) flora may benefit people suffered from hyperoxaluria; a
study showed.

Researchers from Mayo Clinic considered the fact that patients with inflammatory bowel
disease have a 10- to 100-fold increased risk of nephrolithiasis, with enteric hyperoxaluria
being the major risk factor for these and other patients with fat malabsorptive states. They
conducted a study of 10 patients with chronic fat malabsorption, calcium oxalate stones, and
hyperoxaluria to determine if endogenous components of the intestinal microflora can
potentially limit dietary oxalate absorption. For 3 months, they provided patients with doses
of a lactic acid bacteria mixture. After the first month, they found that the mean urinary oxalate
excretion fell by 19%. And, during the third month, urinary oxalate fell 20% from baseline
during the washout period. The supplement reduced calcium oxalate supersaturation
probably due to the decrease in oxalate excretion. [4]

Cranberry juice has been thought to have antilithogenic properties benefiting people suffered
from calcium oxalate urolithiasis. McHarg T and co-workers from University of Cape Town,
South Africa, supplemented a group of 10 South African men with 500 mL of cranberry juice
diluted with 1500 mL tap water for 2 weeks and another group with 2000 mL of tap water for
the same period. They found that the ingestion of cranberry juice significantly and uniquely
altered three key urinary risk factors- calcium oxalate, uric acid and calcium phosphate
saturations. Oxalate and phosphate excretion decreased while citrate excretion increased. In
addition, there was a decrease in the relative super-saturation of calcium oxalate, which
tended to be significantly lower than that induced by water alone. [7]

Other supplements such as Herniaria hirsuta, pyruvate, choreito and urajirogashi are though
to have some benefits in preventing calculi formation, But, more experiments are needed to
confirm the claim. [5, 6]

SOURCES 1 National Kidney and Urologic Diseases Information Clearinghouse 3 Information Way, Bethesda, MD 20892–3580. NIH
Publication No. 05–2495 December 2004.  2. National Kidney and Urologic Diseases Information Clearinghouse 3 Information Way,
Bethesda, MD 20892–3580. NIH Publication No. 04–4154 April 2004 REFERENCE [1] Coe FL and co-workers from University of
Chicago, Illinois Kidney stone disease.J Clin Invest. 2005 Oct;115(10):2598-608. [2] Pragasam V et al, Oral L-arginine supplementation
ameliorates urinary risk factors and kinetic modulation of Tamm-Horsfall glycoprotein in experimental hyperoxaluric rats. Clin Chim
Acta. 2005 Oct;360(1-2):141-50. [3] Massey L  Magnesium therapy for nephrolithiasis. Magnes Res. 2005 Jun;18(2):123-6. [4] Lieske JC
et al, Use of a probiotic to decrease enteric hyperoxaluria. Kidney Int. 2005 Sep;68(3):1244-9. [5] Ogawa Y et al, A comparison
between effects of pyruvate and herb medicines in preventing experimental oxalate urolithiasis in rats. Hinyokika Kiyo. 1986 Aug;32(8):
1127-33. [6] Atmani F and Khan SR Effects of an extract from Herniaria hirsuta on calcium oxalate crystallization in vitro. BJU Int. 2000
Apr;85(6):621-5. [7] McHarg T et al, Influence of cranberry juice on the urinary risk factors for calcium oxalate kidney stone formation.
BJU Int. 2003 Nov;92(7):765-8. [8] Straub M and Hautmann RE, Developments in stone prevention. Curr Opin Urol. 2005 Mar;15(2):119-
26. [9] Kohjimoto Y et al, Future perspective on the prevention of nephrolithiasis Hinyokika Kiyo. 2004 Aug;50(8):591-6.