Kidney Stones Adults

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Kidney Stones

in Adults National Kidney and Urologic Diseases Information Clearinghouse

National

Institute ofDiabetes andDigestiveand Kidney

Diseases

NATIONAL

INSTITUTESOF HEALTH

U.S. Departmentof Health andHuman Services

Kidney stones, one o the most painul o the urologic disorders, have beset humansor centuries. Scientists have ound evi-dence o kidney stones in a 7,000yearold

Egyptian mummy. Unortunately, kidneystones are one o the most common disor-ders o the urinary tract. Each year, peoplemake almost 3 million visits to health careproviders and more than hal a millionpeople go to emergency rooms or kidneystone problems.

Most kidney stones pass out o the body without any intervention by a physician.Stones that cause lasting symptoms or othercomplications may be treated by various

techniques, most o which do not involvemajor surgery. Also, research advanceshave led to a better understanding o themany actors that promote stone ormationand thus better treatments or preventingstones.

Introduction to theUrinary TractThe urinary tract, or system, consists o

the kidneys, ureters, bladder, and urethra.The kidneys are two beanshaped organslocated below the ribs toward the middleo the back, one on each side o the spine.The kidneys remove extra water and wastesrom the blood, producing urine. They alsokeep a stable balance o salts and other substances in the blood. The kidneys producehormones that help build strong bones andorm red blood cells.

Kidneys

UreterBladder

Urethra

The urinary tract.



Narrow tubes called ureters carry urinerom the kidneys to the bladder, an ovalshaped chamber in the lower abdomen.Like a balloon, the bladder’s elastic wallsstretch and expand to store urine. Theyatten together when urine is emptiedthrough the urethra to outside the body.

What is a kidney stone? A kidney stone is a hard mass developedrom crystals that separate rom the urine

within the urinary tract. Normally, urinecontains chemicals that prevent or inhibitthe crystals rom orming. These inhibi-tors do not seem to work or everyone,however, so some people orm stones. I the crystals remain tiny enough, they willtravel through the urinary tract and passout o the body in the urine without beingnoticed.

Kidney stones may contain various combi-nations o chemicals. The most common

type o stone contains calcium in combi-nation with either oxalate or phosphate.These chemicals are part o a person’snormal diet and make up important partso the body, such as bones and muscles.

A less common type o stone is caused byinection in the urinary tract. This type o stone is called a struvite or inection stone. Another type o stone, uric acid stones,are a bit less common, and cystine stonesare rare.

Kidney stones in the kidney, ureter, and bladder.

Urolithiasis is the medical term used todescribe stones occurring in the urinarytract. Other requently used terms are uri-nary tract stone disease and nephrolithiasis.Doctors also use terms that describe thelocation o the stone in the urinary tract.For example, a ureteral stone—or uretero-lithiasis—is a kidney stone ound in theureter. To keep things simple, the generalterm kidney stones is used throughout thisact sheet.

Gallstones and kidney stones are notrelated. They orm in dierent areas o the body. Someone with a gallstone is notnecessarily more likely to develop kidneystones.

Kidney Stones in Adults



Who gets kidney stones?For unknown reasons, the number o people in the United States with kidneystones has been increasing over the past 30 years. In the late 1970s, less than 4 percento the population had stoneorming dis-ease. By the early 1990s, the portion o thepopulation with the disease had increasedto more than 5 percent. Caucasians aremore prone to develop kidney stones than Arican Americans. Stones occur more

requently in men. The prevalence o kid-ney stones rises dramatically as men entertheir 40s and continues to rise into their70s. For women, the prevalence o kidneystones peaks in their 50s. Once a persongets more than one stone, other stones arelikely to develop.

What causes kidney stones?Doctors do not always know what causesa stone to orm. While certain oods may

promote stone ormation in people whoare susceptible, scientists do not believethat eating any specifc ood causes stonesto orm in people who are not susceptible.

A person with a amily history o kidneystones may be more likely to developstones. Urinary tract inections, kidneydisorders such as cystic kidney diseases,and certain metabolic disorders such ashyperparathyroidism are also linked tostone ormation.

In addition, more than 70 percent o people with a rare hereditary disease calledrenal tubular acidosis develop kidneystones.

Staghorn

Smooth

Jagged

Shapes of various stones. Sizes are usually smaller than shown here.

Cystinuria and hyperoxaluria are two otherrare, inherited metabolic disorders thatoten cause kidney stones. In cystinuria,too much o the amino acid cystine, whichdoes not dissolve in urine, is voided, leadingto the ormation o stones made o cystine.In patients with hyperoxaluria, the bodyproduces too much oxalate, a salt. Whenthe urine contains more oxalate than can bedissolved, the crystals settle out and ormstones.

Hypercalciuria is inherited, and it may bethe cause o stones in more than hal o patients. Calcium is absorbed rom ood inexcess and is lost into the urine. This highlevel o calcium in the urine causes crystalso calcium oxalate or calcium phosphateto orm in the kidneys or elsewhere in theurinary tract.

3 Kidney Stones in Adults



Preventing Kidney Stones A person who has had more than one kid-ney stone may be likely to orm another; so,i possible, prevention is important. To helpdetermine their cause, the doctor will orderlaboratory tests, including urine and bloodtests. The doctor will also ask about thepatient’s medical history, occupation, andeating habits. I a stone has been removed,or i the patient has passed a stone andsaved it, a stone analysis by the laboratory

may help the doctor in planning treatment.The doctor may ask the patient to collecturine or 4 hours ater a stone has passedor been removed. For a 4hour urine col-lection, the patient is given a large con-tainer, which is to be rerigerated betweentrips to the bathroom. The collection isused to measure urine volume and levels o acidity, calcium, sodium, uric acid, oxalate,citrate, and creatinine—a product o musclemetabolism. The doctor will use this

inormation to determine the cause o thestone. A second 4hour urine collectionmay be needed to determine whether theprescribed treatment is working.

How are kidney stonestreated?Fortunately, surgery is not usually neces-sary. Most kidney stones can pass throughthe urinary system with plenty o water—to 3 quarts a day—to help move the stonealong. Oten, the patient can stay homeduring this process, drinking uids andtaking pain medication as needed. Thedoctor usually asks the patient to save thepassed stone(s) or testing. It can be caught

in a cup or tea strainer used only or thispurpose.

Lifestyle Changes A simple and most important liestylechange to prevent stones is to drink moreliquids—water is best. Someone who tendsto orm stones should try to drink enoughliquids throughout the day to produce atleast quarts o urine in every 4hourperiod.

In the past, people who orm calcium stones were told to avoid dairy products and otheroods with high calcium content. Recentstudies have shown that oods high incalcium, including dairy products, may helpprevent calcium stones. Taking calcium inpill orm, however, may increase the risk o developing stones.

Patients may be told to avoid ood withadded vitamin D and certain types o ant-acids that have a calcium base. Someone

who has highly acidic urine may need to eatless meat, fsh, and poultry. These oodsincrease the amount o acid in the urine.




Foods and DrinksContaining OxalatePeople prone to orming calcium oxa-late stones may be asked by their doctorto limit or avoid certain oods i theirurine contains an excess o oxalate.

Highoxalate oods—higher to lower

• rhubarb

• spinach• beets

• swiss chard

• wheat germ

• soybean crackers

• peanuts

• okra

• chocolate

• black Indian tea• sweet potatoes

Foods that have medium amountso oxalate may be eaten in limitedamounts.

Mediumoxalate oods—higher to lower

• grits

• grapes

• celery

• green pepper

• red raspberries

• ruit cake

• strawberries

• marmalade

• liver

Source: The Oxalosis and Hyperoxaluria Foundation. ( www.ohf.org/diet.html )

To prevent cystine stones, a person shoulddrink enough water each day to dilute theconcentration o cystine that escapes intothe urine, which may be difcult. Morethan a gallon o water may be needed every4 hours, and a third o that must be drunkduring the night.

Medical Therapy A doctor may prescribe certain medica-tions to help prevent calcium and uricacid stones. These medicines control the

amount o acid or alkali in the urine, keyactors in crystal ormation. The medicineallopurinol may also be useul in some caseso hyperuricosuria.

Doctors usually try to control hypercalci-uria, and thus prevent calcium stones, byprescribing certain diuretics, such as hydro-chlorothiazide. These medicines decreasethe amount o calcium released by thekidneys into the urine by avoring calciumretention in bone. They work best when

sodium intake is low.

Rarely, patients with hypercalciuria aregiven the medicine sodium cellulose phos-phate, which binds calcium in the intestinesand prevents it rom leaking into the urine.

I cystine stones cannot be controlled bydrinking more uids, a doctor may pre-scribe medicines such as Thiola and Cupri-mine, which help reduce the amount o cystine in the urine.

For struvite stones that have been totallyremoved, the frst line o prevention is tokeep the urine ree o bacteria that cancause inection. A patient’s urine will betested regularly to ensure no bacteria arepresent.


http://www.ohf.org/diet.html

http://www.ohf.org/diet.html



I struvite stones cannot be removed, a doc-tor may prescribe a medicine called aceto-hydroxamic acid (AHA). AHA is used withlongterm antibiotic medicines to preventthe inection that leads to stone growth.

People with hyperparathyroidism some-times develop calcium stones. Treatment inthese cases is usually surgery to remove theparathyroid glands, which are located in theneck. In most cases, only one o the glandsis enlarged. Removing the glands cures the

patient’s problem with hyperparathyroidismand kidney stones.

Surgical TreatmentSurgery may be needed to remove a kidneystone i it

• does not pass ater a reasonable periodo time and causes constant pain

• is too large to pass on its own or is caught in a difcult place

• blocks the ow o urine• causes an ongoing urinary tract

inection

• damages kidney tissue or causes con-stant bleeding

• has grown larger, as seen on ollowup x rays

Until 0 years ago, open surgery wasnecessary to remove a stone. The surgeryrequired a recovery time o 4 to weeks.Today, treatment or these stones is greatlyimproved, and many options do not requiremajor open surgery and can be perormedin an outpatient setting.

Shockwaves

Ellipsoidal refector

Shockwavegenerator

Extracorporeal shock wave lithotripsy.

Extracorporeal Shock WaveLithotripsyExtracorporeal shock wave lithotripsy(ESWL) is the most requently used proce-dure or the treatment o kidney stones. InESWL, shock waves that are created out-side the body travel through the skin andbody tissues until they hit the denser stones

The stones break down into small particlesand are easily passed through the urinarytract in the urine.

Several types o ESWL devices exist. Mostdevices use either x rays or ultrasound tohelp the surgeon pinpoint the stone duringtreatment. For most types o ESWL proce-dures, anesthesia is needed.




In many cases, ESWL may be done on anoutpatient basis. Recovery time is rela-tively short, and most people can resumenormal activities in a ew days.

Complications may occur with ESWL.Some patients have blood in their urineor a ew days ater treatment. Bruis-ing and minor discomort in the back orabdomen rom the shock waves can occur.To reduce the risk o complications, doc-tors usually tell patients to avoid taking

aspirin and other medicines that aectblood clotting or several weeks beoretreatment.

Sometimes, the shattered stone par-ticles cause minor blockage as they passthrough the urinary tract and causediscomort. In some cases, the doctor willinsert a small tube called a stent throughthe bladder into the ureter to help theragments pass. Sometimes the stone isnot completely shattered with one treat-

ment, and additional treatments may beneeded.

As with any interventional, surgicalprocedure, potential risks and complica-tions should be discussed with the doctorbeore making a treatment decision.

Percutaneous NephrolithotomySometimes a procedure called percutane-ous nephrolithotomy is recommended toremove a stone. This treatment is otenused when the stone is quite large or in alocation that does not allow eective use oESWL.

In this procedure, the surgeon makes a tinyincision in the back and creates a tunneldirectly into the kidney. Using an instru-ment called a nephroscope, the surgeon

locates and removes the stone. For largestones, some type o energy probe—ultra-sonic or electrohydraulic—may be neededto break the stone into small pieces. Oten,patients stay in the hospital or several daysand may have a small tube called a neph-rostomy tube let in the kidney during thehealing process.

One advantage o percutaneous nephro-lithotomy is that the surgeon can removesome o the stone ragments directly instead

o relying solely on their natural passagerom the kidney.

Nephroscope

Ultrasonicprobe

Percutaneous nephrolithotomy.




Ureteroscopic Stone Removal Although some stones in the ureters canbe treated with ESWL, ureteroscopymay be needed or mid and lowerureterstones. No incision is made in this proce-dure. Instead, the surgeon passes a smallfberoptic instrument called a ureteroscopethrough the urethra and bladder into theureter. The surgeon then locates the stoneand either removes it with a cagelikedevice or shatters it with a special instru-ment that produces a orm o shock wave.

A small tube or stent may be let in the ure-ter or a ew days to help urine ow. Beorefber optics made ureteroscopy possible,physicians used a similar “blind basket”extraction method. But this technique israrely used now because o the higher riskso damage to the ureters.

Ureteroscopic stone removal.

Ureter

Stone

Ureteroscope

Bladder

Stone

Kidney

Ureter

Ureteroscope

Eye piece




Hope Through ResearchThe Division o Kidney, Urologic, andHematologic Diseases o the National Insti-tute o Diabetes and Digestive and KidneyDiseases (NIDDK) unds research on thecauses, treatments, and prevention o kidneystones. The NIDDK is part o the NationalInstitutes o Health in Bethesda, MD.

New medicines and the growing feldo lithotripsy have greatly improved thetreatment o kidney stones. Still, NIDDK

researchers and grantees seek to answerquestions such as

• Why do some people continue to havepainul stones?

• How can doctors predict, or screen,those at risk or getting stones?

• What are the longterm eects o lithotripsy?

• Do genes play a role in stone

ormation?• What is the natural substance(s) ound

in urine that blocks stone ormation?

Researchers are also developing new medi-cines with ewer side eects.

Points to Remember• A person with a amily history o

stones or a personal history o more than one stone may be morelikely to develop more stones.

• A good frst step to prevent theormation o any type o stone isto drink plenty o liquids—water isbest.

• Someone who is at risk or devel-oping stones may need certainblood and urine tests to determine which actors can best be altered toreduce that risk.

• Some people will need medicinesto prevent stones rom orming.

• People with chronic urinary tractinections and stones will otenneed a stone removed i the doctor

determines that the stone is causingthe inection. Patients must receivecareul ollowup to be sure thatthe inection has cleared.




For More Information American Urological Association

Foundation

1000 Corporate BoulevardLinthicum, MD 21090Phone: 1–866–RING–AUA (746–4282) or

410–689–3700Email: [email protected] Internet: www.auaoundation.org

www.UrologyHealth.org

National Kidney Foundation

30 East 33rd StreetNew York, NY 10016Phone: 1–800–622–9010 or 212–889–2210Internet: www.kidney.org

Oxalosis and Hyperoxaluria Foundation

201 East 19th Street, Suite 12ENew York, NY 10003Phone: 1–800–OHF–8699 (643–8699) or

212–777–0470Fax: 212–777–0471Email: [email protected]

Internet: www.oh.org

For Information AboutHyperparathyroidism:National Endocrine and Metabolic

Diseases Information Service

National Institute o Diabetes andDigestive and Kidney DiseasesNational Institutes o Health6 Inormation WayBethesda, MD 20892–3569

Phone: 1–888–828–0904Fax: 703–738–4929Email: [email protected]

For Information About Gout:National Institute of Arthritis and

Musculoskeletal and Skin Diseases

Information Clearinghouse

National Institutes o Health1 AMS CircleBethesda, MD 20892–3675Phone: 1–877–22–NIAMS (226–4267) or

301–495–4484TTY: 301–565–2966Fax: 301–718–6366

Email: [email protected] Internet: www.niams.nih.gov

You may also fnd additional inormation about thistopic by visiting MedlinePlus at www.medlineplus.gov .

This publication may contain inormation aboutmedications used to treat a health condition. Whenthis publication was prepared, the NIDDK includedthe most current inormation available. Occasion-ally, new inormation about medication is released.For updates or or questions about any medications,please contact the U.S. Food and Drug Administra-tion at 1–888–INFO–FDA (463–6332), a tollree call,

or visit their website at www.fda.gov

. Consult yourdoctor or more inormation.


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The U.S. Government does not endorse or avor anyspecifc commercial product or company. Trade,proprietary, or company names appearing in thisdocument are used only because they are considerednecessary in the context o the inormation provided.I a product is not mentioned, the omission does notmean or imply that the product is unsatisactory.

This publication is not copyrighted. The Clearing-house encourages users o this publication to dupli-cate and distribute as many copies as desired.

This act sheet is also available at www.kidney.niddk.nih.gov .

National Kidney andUrologic DiseasesInformation Clearinghouse

3 Inormation WayBethesda, MD 20892–3580Phone: 1–800–891–5390Fax: 703–738–4929Email: [email protected] Internet: www.kidney.niddk.nih.gov

The National Kidney and Urologic Diseases

Inormation Clearinghouse (NKUDIC) is aservice o the National Institute o Diabetesand Digestive and Kidney Diseases (NIDDK).The NIDDK is part o the National Instituteso Health o the U.S. Department o Healthand Human Services. Established in 1987, theClearinghouse provides inormation aboutdiseases o the kidneys and urologic system topeople with kidney and urologic disorders andto their amilies, health care proessionals, andthe public. The NKUDIC answers inquiries,develops and distributes publications, and worksclosely with proessional and patient organiza-

tions and Government agencies to coordinateresources about kidney and urologic diseases.

Publications produced by the Clearinghouseare careully reviewed by both NIDDK scien-tists and outside experts. This publication wasreviewed by Frederic L. Coe., M.D., University

o Chicago.

U.S. DEPARTMENT OF HEALTH

AND HUMAN SERVICES

National Institutes of Health

NIH Publication No. 08–2495October 2007

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