Kidney Stones

What I need to know about

Kidney Stones

NATIONAL INSTITUTES OF HEALTH

National Kidney and Urologic Diseases Information Clearinghouse

U.S. Department

of Health and

Human Services
What I need to know

about Kidney Stones

NATIONAL INSTITUTES OF HEALTH

National Kidney and Urologic Diseases Information Clearinghouse
Contents

When should I call a doctor?.................................. 1

What do my kidneys do?......................................... 2

What is a kidney stone? .......................................... 3

Are all kidney stones alike?.................................... 4

What do kidney stones look like? .......................... 5

What can my doctor do about a problem 

stone?........................................................................ 6

How will my doctor find out what kind of 

stone I have? ............................................................ 8

Why do I need to know the kind of stone? ........... 8

What can I do to avoid more stones? .................... 9

Points to Remember.............................................. 10

For More Information........................................... 11

Acknowledgments ................................................. 12
When should I call a doctor?

If you have a kidney stone, you may already know

how painful it can be. 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. Your doctor can help.

You should call a doctor when you have

● extreme pain in your

back or side that will

not go away

● blood in your urine

● fever and chills

● vomiting

● urine that smells bad

or looks cloudy

● a burning feeling when

you urinate

These may be signs of a

kidney stone that needs a

doctor’s care.

1

Pain in the shaded areas

may be caused by kidney

stones.
What do my kidneys do?

Your kidneys are bean-shaped organs, each about

the size of your fist. They are located near the

middle of your back, just below the rib cage. The

kidneys are sophisticated trash collectors. Every

day, your 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 your bladder

through tubes called ureters (YOOR-uh-turs).

Your bladder (BLAD-ur) stores urine until you

go to the bathroom.

2

Wastes removed from the blood go to

the bladder.

Kidneys

Ureters

Bladder

Urethra

Clean blood

Blood with

wastes

Wastes (urine) to the bladder
The wastes in your blood come from the normal

breakdown of active muscle and from the food you

eat. Your body uses the food for energy and selfrepair. 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.

In addition to removing wastes, your kidneys help

control blood pressure. They also help to make

red blood cells and keep your bones strong.

What is a kidney stone?

A kidney stone is a solid piece of material that

forms in the kidney out of substances in the urine. 

A stone may stay in the kidney or break loose and

travel down the urinary tract. A small stone may

pass all the way out of the body without causing too

much pain.

A larger stone may get stuck in a ureter, the

bladder, or the urethra. A problem stone can

block the flow of urine and cause great pain.

3
Are all kidney stones alike?

No. There are four major types of kidney stones.

● The most common type of stone contains

calcium (KAL-see-um). Calcium is a normal

part of a healthy diet. 

Calcium that is not used by the bones and

muscles goes to the kidneys. In most people,

the kidneys flush out the extra calcium with the

rest of the urine. People who have calcium

stones keep the calcium in their kidneys. 

The calcium that stays behind joins with other

waste products to form a stone.

● A struvite (STROO-vite) stone may form after

an infection in the urinary system. These stones

contain the mineral magnesium (mag-NEE-zeeum) and the waste product ammonia (uh-MOHnyuh).

● A uric (YOOR-ik) 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 (SIS-teen) 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.

What do kidney stones look like?

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.

5

Kidney stones vary in size and shape. These are not actual

size.

Small and smooth

Golf ball sized

and brown

Jagged and yellow
What can my doctor do about

a problem stone?

If you have a stone that will not pass by itself, your

doctor may need to take steps to get rid of it. In

the past, the only way to remove a problem stone

was through surgery.

Now, doctors have new ways to remove problem

stones. The following pages describe a few of these

methods.

Shock Waves

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

(EKS-trah-kor-POR-ee-ul) shock wave lithotripsy

(LITH-oh-TRIP-see). Doctors often call it ESWL

for short. Lithotripsy is a Greek word that means

stone crushing.

6
Tunnel Surgery

In this method, the doctor makes a small cut into

the patient’s back and makes a narrow tunnel

through the skin to the stone inside the kidney.

With a special instrument that goes through the

tunnel, the doctor can find the stone and 

remove it. The technical name for this method 

is percutaneous (PER-kyoo-TAY-nee-us)

nephrolithotomy (NEF-row-lith-AH-tuh-mee).

Ureteroscope

A ureteroscope (yoo-REE-ter-uh-scope) 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 ureteroscope.

Ask your doctor which method is right for you.

7
How will my doctor find out 

what kind of stone I have?

The best way for your doctor to find out what kind

of stone you have is to test the stone itself. If you

know that you are passing a stone, try to catch it in

a strainer.

Your doctor may ask

for a urine sample or

take blood to find out

what is causing your

stones. You may need

to collect your urine for

a 24-hour period.

These tests will help

your doctor find ways

for you to avoid stones

in the future.

Why do I need to know the 

kind of stone?

The therapy your doctor gives you depends on the

type of stone you have. For example, a medicine

that helps prevent calcium stones will not work if

you have a struvite stone. The diet changes that

help prevent uric acid stones may have no effect on

calcium stones. Therefore, careful analysis of the

stone will help guide your treatment.

8

Try to catch a stone in a strainer.
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.

9

Try to drink 12 full glasses of water

every day.
Points to Remember

● Most stones will pass out of the body without a

doctor’s help.

● See your doctor if you have severe pain in your

back or side that will not go away.

● See your doctor if you have blood in your urine

(urine will appear pink).

● Drink lots of water to prevent more kidney

stones from forming.

● When you pass a stone, try to catch it in a

strainer to show to your doctor.

● Talk to your doctor about how to avoid more

stones.

10
For More Information

American Foundation for Urologic Disease

1000 Corporate Boulevard, Suite 410

Linthicum, MD 21090

Phone: 1–800–828–7866 or (410) 689–3990

Fax: (410) 689–3998

Email: admin@afud.org

Internet: www.afud.org

National Kidney Foundation

30 East 33rd Street

New York, NY 10016

Phone: 1–800–622–9010 or (212) 889–2210

Email: info@kidney.org

Internet: www.kidney.org

Oxalosis and Hyperoxaluria Foundation (OHF)

201 E. 19th Street, #12E

New York, NY 10003

Phone: 1–800–OHF–8699 or (212) 777–0470

Fax: (212) 777–0471

Email: execdirector@ohf.org

Internet: www.ohf.org

11
Acknowledgments

The individuals listed here provided editorial

guidance or facilitated field testing for this

publication. The National Kidney and Urologic

Diseases Information Clearinghouse (NKUDIC)

would like to thank these individuals for their

contribution.

12

John Aspin, M.D.

The University of 

Chicago Hospitals

Chicago, IL

Anne Gaddy

Zacchaeus Free Clinic

Washington, DC

Pamela Grigsby, P.A.

Washington Nephrology

Associates

Bethesda, MD

Charlotte Szromba,

M.S.N., R.N., C.N.N.

The University of

Chicago Hospitals

Chicago, IL

Judith Thomas

American Society of

Nephrology

Washington, DC 

Gail Wick, R.N., B.S.N.

American Nephrology

Nurses’ Association

Atlanta, GA
National Kidney and Urologic

Diseases Information Clearinghouse

3 Information Way

Bethesda, MD 20892–3580

Phone: 1–800–891–5390 or (301) 654–4415

Fax: (301) 907–8906

Email: nkudic@info.niddk.nih.gov

Internet: www.urologic.niddk.nih.gov

The National Kidney and Urologic Diseases Information

Clearinghouse (NKUDIC) is a service of the National

Institute of Diabetes and Digestive and Kidney Diseases

(NIDDK). The NIDDK is part of the National Institutes of

Health under the U.S. Department of Health and Human

Services. Established in 1987, the clearinghouse provides

information about diseases of the kidneys and urologic

system to people with kidney and urologic disorders and

to their families, health care professionals, and the public.

NKUDIC answers inquiries, develops and distributes

publications, and works closely with professional and

patient organizations and Government agencies to

coordinate resources about kidney and urologic diseases.

Publications produced by the clearinghouse are carefully

reviewed by both NIDDK scientists and outside experts.

This publication is not copyrighted. The clearinghouse

encourages users of this booklet to duplicate and

distribute as many copies as desired.

This booklet is also available at www.urologic.niddk.nih.gov.
National Institute of Diabetes and 

Digestive and Kidney Diseases

NIH Publication No. 04–4154

April 2004

U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES

National Institutes of Health