Explains why and how kidney stones form. Covers types of stones such as calcium, cystine, uric acid, and struvite. Discusses symptoms. Covers treatment, including extracorporeal shock wave lithotripsy and ureteroscopy. Offers prevention tips.
What are kidney stones?
Kidney stones are made of
salts and minerals in the urine that stick together to form small "pebbles."
They can be as small as grains of sand or as large as golf balls. They may stay
kidneys or travel out of your body through the
urinary tract. The urinary tract is the system that makes urine and carries it
out of your body. It is made up of the kidneys, the tubes that connect the
kidneys to the bladder (the
ureters), the bladder, and the tube that leads from
the bladder out of the body (the
Kidney stones form when
a change occurs in the normal balance of water, salts, minerals, and other
things found in urine. The most common cause of kidney stones is not drinking
enough water. Try to drink enough water, enough so that your urine is light yellow or clear like water (about 8 to 10
glasses a day). Some people are more likely to get kidney stones
because of a medical condition, such as gout.
may also be an inherited disease. If other people in your family have had
kidney stones, you may have them too.
What are the symptoms?
Kidney stones often cause
no pain while they are in the kidneys. But they can cause sudden, severe pain
as they travel from the kidneys to the bladder.
Call a doctor
right away if you think you have kidney stones. Watch for severe pain in your
side, belly, or groin or for urine that looks pink or red. You may also feel
sick to your stomach (nausea) and may vomit.
How are kidney stones diagnosed?
You may first
find out that you have kidney stones when you see your doctor or go to an
emergency room with pain in your belly or side. Your doctor will ask you
questions about your pain and lifestyle. He or she will examine you and may do
imaging tests such as
a CT scan or an ultrasound to look at your kidneys and urinary tract.
You may need more tests if you have more than one stone or have
a family history of stones. To find out the cause of your kidney stones, your
doctor may order a blood test and ask you to collect your urine for 24 hours.
This can help your doctor find out if you are likely to have more stones in the
Kidney stones may not cause any pain. If this is the case,
you may learn you have them when your doctor finds them during a test for
How are they treated?
For most stones, your doctor
will suggest that you take care of yourself at home. You may need to take pain
medicine. You'll need to drink enough water and other fluids so you don't get
dehydrated. Your doctor may give you a medicine to
help the stone pass.
If a stone is too large to pass on its own,
or if it gets stuck in the urinary tract, you may need more treatment.
The most common treatment is
extracorporeal shock wave lithotripsy (ESWL). ESWL uses shock waves to break a
kidney stone into small pieces. The bits can pass out of your body in your
urine. Other times, a doctor will need to remove the stone or place a small
flexible plastic tube (called a
stent) in the ureter to keep it open while stones
How can you prevent kidney stones?
After you have
had kidney stones, you are more likely to have them again. You can help prevent
them by drinking plenty of water, enough so that your urine is light yellow or clear like water, about 8 to 10 glasses
of water a day. You may have to eat less of certain foods. Your doctor may also
give you medicine that helps prevent stones from forming.
may form when the normal balance of water, salts, minerals, and other
substances found in urine changes. How this balance changes determines the type
of kidney stone you have. Most kidney stones are
calcium-type—they form when the
calcium levels in your urine change.
Things that change your urine balance include:
Not drinking enough water. When you
don't drink enough water, the salts, minerals, and other substances in the
urine can stick together and form a stone. This is the most common cause of
Medical conditions. Many medical conditions can
affect the normal balance and cause stones to form. Examples include
gout and inflammatory bowel disease, such as Crohn's disease.
More commonly, kidney stones can run in families, as stones
often occur in family members over several generations.
cases, a person forms kidney stones because the
parathyroid glands produce too much of a hormone. This leads to higher calcium levels and possibly calcium kidney stones.
form in the kidney. If they stay in the kidney, they typically do not cause
pain. When they travel out of the body through the tubes of the
urinary tract (including the
ureters, which connect the kidney to the bladder, or
urethra, which leads outside the body), their movement
No symptoms, if the stone is small enough.
Sudden, severe pain that gets worse in waves. Stones may cause
intense pain in the back, side, abdomen, groin, or genitals. People who have
had a kidney stone often describe the pain as "the worst pain I've ever had."
Feeling sick to the stomach (nausea) and
Blood in the urine (hematuria), which can occur either
with stones that stay in the kidney or with those that travel through the
Frequent and painful urination, which may occur when the
stone is in the ureter or after the stone has left the bladder and is in the
urethra. Painful urination may occur when a
urinary tract infection is also present.
Conditions with similar symptoms
ectopic pregnancy, and
kidney stone begins as a tiny piece of crystal in the
kidney. When the urine leaves the kidney, it may carry the crystal out, or the
crystal may stay in the kidney. If the crystal stays in the kidney, over time
more small crystals join it and form a larger kidney stone.
stones leave the kidney and travel through the
urinary tract when they are still small enough to pass easily out of the body.
No treatment is needed for these stones.
Larger stones may become stuck
in the tubes that carry urine from the kidney to the bladder (ureters). This can cause pain and possibly block the
urine from flowing to the bladder and out of the body. The pain often becomes
worse over 15 to 60 minutes until it is severe. The pain may ease when the
stone no longer blocks the flow of urine. And the pain often goes away when the stone
passes into the bladder. Medical treatment is often needed for larger
Problems that may occur with kidney stones include:
Kidney damage, if stones block the flow of
urine out of both kidneys (or out of one kidney, for people who have a single
kidney). For most people with healthy kidneys, kidney stones do not cause
serious damage until they completely block the urinary tract for 2 weeks or
Kidney stones are more serious for people who have a single
kidney or an
impaired immune system or have had a kidney
Stones in pregnant women
When stones occur during
urologist should determine whether you need treatment.
Treatment will depend on your trimester of pregnancy.
What Increases Your Risk
Several risk factors (things that put you at risk) for kidney stones make it more
likely that you will get
them. Some of these things you can control, and
others you cannot.
Risk factors you can control
Things you can control include:
How much fluid you drink.
The most common cause of kidney stones is
not drinking enough water. Try to drink enough water to keep your urine light yellow or clear like water
(about 8 to 10 glasses of water a day).
Your diet. Diets high in protein, sodium, and
oxalate-rich foods, such as dark green vegetables,
increase your risk for kidney stones. If you think that your diet may be a
problem, schedule an appointment with a
dietitian and review your food choices.
Your first diagnosis of
kidney stones often occurs when you see your doctor or
go to an emergency room because you are in great pain. Your doctor or an
emergency medicine specialist will ask you questions and
examine you. After you pass a
stone, your doctor may give you another exam to find out whether you are likely
to get kidney stones again.
Tests to diagnose kidney stones
Your doctor may do
one or more of the following tests to help diagnose kidney stones, see where they are
located, and find out if they are causing or may cause damage to the
spiral computed tomography (CT) scan is the preferred
test for kidney stones. It is a special type of CT scan that moves in a circle.
Stone analysis. Your doctor may ask you
to collect stones by straining your urine through a fine-mesh strainer or fine
gauze. He or she will then determine what type of stone it
Blood chemistry screen, to measure kidney function,
levels of calcium, uric acid, phosphorus, electrolytes, and other substances
that may have caused the stone to form.
Urine collection for 24 hours, to measure volume, pH, calcium, oxalate, uric
acid, and other substances that may have caused the stone to form. This is a test you may do at home.
For small stones, most people don't need any treatment other than taking pain medicine
and drinking enough fluids.
Treatment for your first stone
If your doctor
thinks the stone can pass on its own, and if you feel you can deal with the pain,
he or she may suggest home treatment, including:
Using pain medicine. Nonprescription medicine, such as
nonsteroidal anti-inflammatory drugs (NSAIDs), may relieve
your pain. Be safe with medicines. Read and follow all instructions on the label. Your doctor can prescribe stronger pain medicine if
Drinking enough fluids. You'll need to keep drinking water
and other fluids when you are passing a kidney stone.
Your doctor may prescribe medicine to help your body pass
To learn more, see Medications.
If your pain is too
severe, if the stones are blocking the
urinary tract, or if you also have an infection, your doctor will probably
suggest a medical procedure, such as lithotripsy, or surgery to deal with the stone. For more information, see Other Treatment and Surgery.
After you have had a
kidney stone, you are more likely to have one again.
You may be able to prevent
getting more kidney stones by drinking more fluids and making changes in your
diet. Talk with your doctor or a dietitian if you need help with your diet. If you have risk factors (things that put you at risk) for having more stones, such as a family history
of stones, your doctor may suggest medicines that help prevent stones from
After you have had a kidney stone, you are more likely to have stones again. But you can take
steps to help prevent them:
Drink more fluids. Try to drink enough water to
keep your urine light yellow or clear like water, about 8 to 10 glasses of water a day. Slowly increase
how much you drink, perhaps adding one more glass of water a day until you are
drinking 8 to 10 glasses a day. This slow increase will give your body time to
adjust to the extra fluids. If your urine is dark yellow, you are not drinking enough
fluids. If you have kidney, heart, or liver disease and have fluid
restrictions, talk with your doctor before increasing how much you
Change your diet. This may be helpful, but it depends on
what is causing your kidney stones. Your doctor may do more tests before
deciding whether changing your diet will help reduce your risk for getting
If you get more kidney stones despite
drinking more fluids and making changes to your diet, your doctor may give you
medicine to help dissolve your stones or to prevent new ones from forming. For more
information, see Medications.
Home treatment—drinking more fluids and taking pain medicine—is often the only thing
you need to do when passing a
When you are
passing a kidney stone, you need to drink enough water to
keep your urine light yellow or clear like water, about 8 to 10 glasses of water a day. If you have kidney, heart, or liver disease and are on
fluid restrictions, talk with your doctor before drinking more fluids.
Use pain medicine
Medicine you can buy without a
prescription, such as
nonsteroidal anti-inflammatory drugs (NSAIDs), may relieve
your pain. NSAIDs include aspirin and ibuprofen (such as Advil and Motrin).
Be safe with medicines. Read and follow all instructions on the label. Your doctor can prescribe stronger pain medicine if needed.
Some struvite stones (staghorn calculi) form because of
kidney infections. If you have a struvite stone, you
will most likely need antibiotics to cure the infection and help prevent new
stones from forming. You may need surgery to remove the
stone. Urease inhibitors may be used to prevent struvite stones.
Surgery is rarely needed to treat kidney stones. Surgery is only needed when the kidney stone is very large, caused by an infection (staghorn calculi), blocking the flow of urine out of the kidney, or causing other problems like severe bleeding.
In open surgery, the surgeon makes a cut in your side or stomach to reach the kidneys. He or she removes the stone.
If your kidney stones were caused by a problem with your parathyroid gland, your doctor may suggest surgery to
remove a parathyroid gland or glands (parathyroidectomy). This can help prevent future kidney stones.
Other treatments for kidney stones are much more common than surgery. You may need one of these treatments if your pain is very bad, your stone is blocking the urinary tract, or you have an infection. Your options include:
National Kidney and Urologic Diseases Information
3 Information Way
Bethesda, MD 20892-3580
The National Kidney and Urologic Diseases Information
Clearinghouse (NKUDIC) provides information about diseases of the
kidneys and urologic system to people with these problems and to
their families, to health professionals, and to the public. NKUDIC answers
inquiries; develops, reviews, and distributes publications; and works closely
with professional and patient groups and government agencies to
coordinate resources about kidney and urologic diseases.
NKUDIC, a federal agency, is a service of the National
Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). NIDDK is part
of the National Institutes of Health under the U.S. Department of Health and
National Kidney Foundation
30 East 33rd Street
New York, NY 10016
The National Kidney Foundation works to prevent kidney
and urinary tract diseases and help people affected by these conditions. Its
website has a lot of information about adult and child conditions. The site
has interactive tools, donor information, recipes for kidney disease patients,
and message boards for many kidney topics. Free materials, such as brochures
and newsletters, are available.
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E. Gregory Thompson, MD - Internal Medicine
Tushar J. Vachharajani, MD, FASN, FACP - Nephrology
How this information was developed to help you make better health decisions.