Kidney Stones

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Definition & Facts

What are kidney stones?

Kidney stones are hard, pebble-like pieces of material that form in one or both of your kidneys when high levels of certain minerals are in your urine. Kidney stones rarely cause permanent damage if treated by a health care professional.

Kidney stones vary in size and shape. They may be as small as a grain of sand or as large as a pea. Rarely, some kidney stones are as big as golf balls. Kidney stones may be smooth or jagged and are usually yellow or brown.

A small kidney stone may pass through your urinary tract on its own, causing little or no pain. A larger kidney stone may get stuck along the way. A kidney stone that gets stuck can block your flow of urine, causing severe pain or bleeding. Learn more about your urinary tract and how it works.

If you have symptoms of kidney stones, including severe pain or bleeding, seek care right away. A doctor, such as a urologist, can treat any pain and prevent further problems, such as a urinary tract infection (UTI).

Illustration of a human kidney with several kidney stones blocking the urinary tract.
A small kidney stone may pass through your urinary tract on its own, causing little or no pain. A larger kidney stone may get stuck along the way.

Do kidney stones have another name?

The scientific name for a kidney stone is renal calculus or nephrolith. You may hear health care professionals call this condition nephrolithiasis or urolithiasis.

What type of kidney stones do I have?

You probably have one of four main types of kidney stones. Treatment for kidney stones usually depends on their size, location, and what they are made of.

Calcium stones

Calcium stones, including calcium oxalate stones and calcium phosphate stones, are the most common types of kidney stones. Calcium oxalate stones are more common than calcium phosphate stones.

Calcium from food does not increase your chance of having calcium oxalate stones. Normally, extra calcium that isn’t used by your bones and muscles goes to your kidneys and is flushed out with urine. When this doesn’t happen, the calcium stays in the kidneys and joins with other waste products to form a kidney stone.

Uric acid stones

A uric acid stone may form when your urine contains too much acid. Eating a lot of fish, shellfish, and meat—especially organ meat—may increase uric acid in urine.

Struvite stones

Struvite stones may form after you have a UTI. They can develop suddenly and become large quickly.

Cystine stones

Cystine stones result from a disorder called cystinuria that is passed down through families. Cystinuria causes the amino acid cystine to leak through your kidneys and into the urine.

How common are kidney stones?

Kidney stones are common and are on the rise. About 11 percent of men and 6 percent of women in the United States have kidney stones at least once during their lifetime.1

Who is more likely to develop kidney stones?

Men are more likely to develop kidney stones than women. If you have a family history of kidney stones, you are more likely to develop them. You are also more likely to develop kidney stones again if you’ve had them once.

You may also be more likely to develop a kidney stone if you don’t drink enough liquids.

People with certain conditions

You are more likely to develop kidney stones if you have certain conditions, including

  • a blockage of the urinary tract
  • chronic, or long-lasting, inflammation of the bowel
  • cystic kidney diseases, which are disorders that cause fluid-filled sacs to form on the kidneys
  • cystinuria
  • digestive problems or a history of gastrointestinal tract surgery
  • gout, a disorder that causes painful swelling of the joints
  • hypercalciuria, a condition that runs in families in which urine contains unusually large amounts of calcium; this is the most common condition found in people who form calcium stones
  • hyperoxaluria, a condition in which urine contains unusually large amounts of oxalate
  • hyperparathyroidism, a condition in which the parathyroid glands release too much parathyroid hormone, causing extra calcium in the blood
  • hyperuricosuria, a disorder in which too much uric acid is in the urine
  • obesity
  • repeated, or recurrent, UTIs
  • renal tubular acidosis, a disease that occurs when the kidneys fail to remove acids into the urine, which causes a person’s blood to remain too acidic

People who take certain medicines

You are more likely to develop kidney stones if you are taking one or more of the following medicines over a long period of time:

What are the complications of kidney stones?

Complications of kidney stones are rare if you seek treatment from a health care professional before problems occur.

If kidney stones are not treated, they can cause

References

Symptoms & Causes

What are the symptoms of kidney stones?

Symptoms of kidney stones include

  • sharp pains in your back, side, lower abdomen, or groin
  • pink, red, or brown blood in your urine, also called hematuria
  • a constant need to urinate
  • pain while urinating
  • inability to urinate or can only urinate a small amount
  • cloudy or bad-smelling urine

See a health care professional right away if you have any of these symptoms. These symptoms may mean you have a kidney stone or a more serious condition.

Your pain may last for a short or long time or may come and go in waves. Along with pain, you may have

  • nausea
  • vomiting

Other symptoms include

  • fever
  • chills
Photo of a man suffering from sharp pains in his lower back.
You may have a kidney stone if you have pain while urinating or feel a sharp pain in your back or lower abdomen.

What causes kidney stones?

Kidney stones are caused by high levels of calcium, oxalate, and phosphorus in the urine. These minerals are normally found in urine and do not cause problems at low levels.

Certain foods may increase the chances of having a kidney stone in people who are more likely to develop them.

Diagnosis

How do health care professionals diagnose kidney stones?

Health care professionals use your medical history, a physical exam, and lab and imaging tests to diagnose kidney stones.

A health care professional will ask if you have a history of health conditions that make you more likely to develop kidney stones. The health care professional also may ask if you have a family history of kidney stones and about what you typically eat. During a physical exam, the health care professional usually examines your body. The health care professional will ask you about your symptoms.

Photo of a woman who is reclining in a doctor’s office and looking at a health care professional who is taking notes.
A health care professional will ask if you have a history of health conditions that make you more likely to develop kidney stones.

What tests do health care professionals use to diagnose kidney stones?

Health care professionals may use lab or imaging tests to diagnose kidney stones.

Lab tests

Urine tests can show whether your urine contains high levels of minerals that form kidney stones. Urine and blood tests can also help a health care professional find out what type of kidney stones you have.

Urinalysis. Urinalysis involves a health care professional testing your urine sample. You will collect a urine sample at a doctor’s office or at a lab, and a health care professional will test the sample. Urinalysis can show whether your urine has blood in it and minerals that can form kidney stones. White blood cells and bacteria in the urine mean you may have a urinary tract infection.

Blood tests. A health care professional may take a blood sample from you and send the sample to a lab to test. The blood test can show if you have high levels of certain minerals in your blood that can lead to kidney stones.

Imaging tests

Health care professionals use imaging tests to find kidney stones. The tests may also show problems that caused a kidney stone to form, such as a blockage in the urinary tract or a birth defect. You do not need anesthesia for these imaging tests.

Abdominal x-ray. An abdominal x-ray is a picture of the abdomen that uses low levels of radiation and is recorded on film or on a computer. An x-ray technician takes an abdominal x-ray at a hospital or outpatient center, and a radiologist reads the images. During an abdominal x-ray, you will lie on a table or stand up. The x-ray technician will position the x-ray machine over or in front of your abdomen and ask you to hold your breath so the picture won’t be blurry. The x-ray technician then may ask you to change position for additional pictures. Abdominal x-rays can show the location of kidney stones in the urinary tract. Not all stones are visible on abdominal x-ray.

Computed tomography (CT) scans. CT scans use a combination of x-rays and computer technology to create images of your urinary tract. Although a CT scan without contrast medium is most commonly used to view your urinary tract, a health care professional may give you an injection of contrast medium. Contrast medium is a dye or other substance that makes structures inside your body easier to see during imaging tests. You’ll lie on a table that slides into a tunnel-shaped device that takes the x-rays. CT scans can show the size and location of a kidney stone, if the stone is blocking the urinary tract, and conditions that may have caused the kidney stone to form.

Treatment

How do health care professionals treat kidney stones?

Health care professionals usually treat kidney stones based on their size, location, and what type they are.

Small kidney stones may pass through your urinary tract without treatment. If you’re able to pass a kidney stone, a health care professional may ask you to catch the kidney stone in a special container. A health care professional will send the kidney stone to a lab to find out what type it is. A health care professional may advise you to drink plenty of liquids if you are able to help move a kidney stone along. The health care professional also may prescribe pain medicine.

Larger kidney stones or kidney stones that block your urinary tract or cause great pain may need urgent treatment. If you are vomiting and dehydrated, you may need to go to the hospital and get fluids through an IV.

Kidney stone removal

A urologist can remove the kidney stone or break it into small pieces with the following treatments:

Shock wave lithotripsy. The doctor can use shock wave lithotripsy to blast the kidney stone into small pieces. The smaller pieces of the kidney stone then pass through your urinary tract. A doctor can give you anesthesia during this outpatient procedure.

Cystoscopy and ureteroscopy. During cystoscopy, the doctor uses a cystoscope to look inside the urethra and bladder to find a stone in your urethra or bladder. During ureteroscopy, the doctor uses a ureteroscope, which is longer and thinner than a cystoscope, to see detailed images of the lining of the ureters and kidneys. The doctor inserts the cystoscope or ureteroscope through the urethra to see the rest of the urinary tract. Once the stone is found, the doctor can remove it or break it into smaller pieces. The doctor performs these procedures in the hospital with anesthesia. You can typically go home the same day.

Percutaneous nephrolithotomy. The doctor uses a thin viewing tool, called a nephroscope, to locate and remove the kidney stone. The doctor inserts the tool directly into your kidney through a small cut made in your back. For larger kidney stones, the doctor also may use a laser to break the kidney stones into smaller pieces. The doctor performs percutaneous nephrolithotomy in a hospital with anesthesia. You may have to stay in the hospital for several days after the procedure.

After these procedures, sometimes the urologist may leave a thin flexible tube, called a ureteral stent, in your urinary tract to help urine flow or a stone to pass. Once the kidney stone is removed, your doctor sends the kidney stone or its pieces to a lab to find out what type it is.

The health care professional also may ask you to collect your urine for 24 hours after the kidney stone has passed or been removed. The health care professional can then measure how much urine you produce in a day, along with mineral levels in your urine. You are more likely to form stones if you don’t make enough urine each day or have a problem with high mineral levels.

Kidney stones of varying sizes and shapes.
Health care professionals usually treat kidney stones based on their size and what they are made of.

How can I prevent kidney stones?

To help prevent future kidney stones, you also need to know what caused your previous kidney stones. Once you know what type of kidney stone you had, a health care professional can help you make changes to your eating, diet, and nutrition to prevent future kidney stones.

Drinking liquids

In most cases, drinking enough liquids each day is the best way to help prevent most types of kidney stones. Drinking enough liquids keeps your urine diluted and helps flush away minerals that might form stones.

Though water is best, other liquids such as citrus drinks may also help prevent kidney stones. Some studies show that citrus drinks, such as lemonade and orange juice, protect against kidney stones because they contain citrate, which stops crystals from turning into stones.

Unless you have kidney failure, you should drink six to eight, 8-ounce glasses a day. If you previously had cystine stones, you may need to drink even more. Talk with a health care professional if you can’t drink the recommended amount due to other health problems, such as urinary incontinence, urinary frequency, or kidney failure.

The amount of liquid you need to drink depends on the weather and your activity level. If you live, work, or exercise in hot weather, you may need more liquid to replace the fluid you lose through sweat. A health care professional may ask you to collect your urine for 24 hours to determine the amount of urine you produce a day. If the amount of urine is too low, the health care professional may advise you to increase your liquid intake.

Medicines

If you have had a kidney stone, a health care professional also may prescribe medicines to prevent future kidney stones. Depending on the type of kidney stone you had and what type of medicine the health care professional prescribes, you may have to take the medicine for a few weeks, several months, or longer.

For example, if you had struvite stones, you may have to take an oral antibiotic for 1 to 6 weeks, or possibly longer.

If you had another type of stone, you may have to take a potassium citrate tablet 1 to 3 times daily. You may have to take potassium citrate for months or even longer until a health care professional says you are no longer at risk for kidney stones.

Type of kidney stone Possible medicines prescribed by your doctor
Calcium Stones
  • potassium citrate, which is used to raise the citrate and pH levels in urine
  • diuretics, often called water pills, help rid your body of water
Uric Acid Stones
  • allopurinol, which is used to treat high levels of uric acid in the body
  • potassium citrate
Struvite Stones
  • antibiotics, which are bacteria-fighting medications
  • acetohydroxamic acid, a strong antibiotic, used with another long-term antibiotic medication to prevent infection
Cystine Stones
  • mercaptopropionyl glycine, an antioxidant used for heart problems
  • potassium citrate

Talk with a health care professional about your health history prior to taking kidney stone medicines. Some kidney stone medicines have minor to serious side effects. Side effects are more likely to occur the longer you take the medicine and the higher the dose. Tell the health care professional about any side effects that occur when you take kidney stone medicine.

Hyperparathyroidism surgery

People with hyperparathyroidism, a condition that results in too much calcium in the blood, sometimes develop calcium stones. Treatment for hyperparathyroidism may include surgery to remove the abnormal parathyroid gland. Removing the parathyroid gland cures hyperparathyroidism and can prevent kidney stones. Surgery sometimes causes complications, including infection.

Eating, Diet, & Nutrition

Can what I eat help prevent future kidney stones?

You may be able to prevent future kidney stones by making changes in how much sodium, animal protein, calcium, or oxalate you consume. A dietitian who specializes in kidney stone prevention can help you plan meals.

You can make changes to what you eat based on the type of kidney stone you had. Details of the suggested changes follow this chart.

Type of kidney stone Helpful change in diet and nutrition
Calcium Oxalate Stones
  • Reduce sodium
  • Limit animal protein
  • Reduce oxalate
  • Get enough calcium from foods
Calcium Phosphate Stones
  • Reduce sodium
  • Reduce animal protein
  • Get enough calcium from foods
Uric Acid Stones
  • Limit animal protein

Reduce sodium

Talk with a health care professional about how much sodium should be in what you eat, especially if you had calcium oxalate stones or calcium phosphate stones.

Most Americans consume too much sodium. Sodium is a part of salt. Sodium is in many canned, packaged, and fast foods. Sodium is also in many condiments, seasonings, and meats. Your chance of developing kidney stones increases when you eat more sodium.

Dietary Guidelines for Americans 2015-2020 provides information on how much sodium an adult should have each day.2 If you have had calcium oxalate or calcium phosphate stones, you should follow this guideline even if you take medicine to prevent kidney stones.

Here are some tips to help reduce your sodium intake:

  • Check the Percent Daily Value (%DV) for sodium on Nutrition Facts label, found on many foods. Low in sodium is 5% or less and high in sodium is 20% or more.
  • Consider writing down how much sodium you consume each day.
  • When eating out, ask about the sodium content in the food.
  • Avoid processed and fast foods, canned soups and vegetables, and lunch meats.

Check labels for ingredients and hidden sodium, such as

  • sodium bicarbonate, the chemical name for baking soda
  • baking powder, which contains sodium bicarbonate and other chemicals
  • disodium phosphate
  • monosodium glutamate, or MSG
  • sodium alginate
  • sodium nitrate or nitrite
A photo of a woman and a man who are cooking a healthy meal in a kitchen.
To reduce sodium to help prevent kidney stones, avoid processed and fast foods, canned soups and vegetables, and lunch meats.

Limit animal protein

Eating animal protein may increase your chances of developing kidney stones.

A health care professional may tell you to limit eating animal protein, including

  • beef, chicken, and pork, especially organ meat
  • eggs
  • fish and shellfish
  • milk, cheese, and other dairy products

Although you may need to reduce how much animal protein you have each day, you still need to make sure you get enough. Talk with the health care professional about how much animal protein you should eat.

Consider replacing some of the meat and animal protein you would typically eat with some of these plant-based foods that are high in protein:

  • legumes such as beans, dried peas, lentils, and peanuts
  • soy foods, such as soy milk, soy nut butter, and tofu
  • nuts and nut products, such as almonds and almond butter, cashews and cashew butter, walnuts, and pistachios
  • sunflower seeds

IMPORTANT NOTE: If you have had calcium oxalate stones, avoid peanuts, soy foods, nuts and nut products, and sunflower seeds.

Reduce oxalate

You may want to avoid these foods to help reduce the amount of oxalate in your urine:

  • nuts and nut products
  • peanuts, which are legumes
  • rhubarb
  • spinach
  • wheat bran

Talk with a health care professional about other food sources of oxalate and how much oxalate should be in what you eat, especially if you have had calcium oxalate stones.

Get enough calcium

Talk with a health care professional about how much calcium you should eat, especially if you had calcium stones. Even though calcium sounds like it would be the cause of calcium stones, it’s not. Calcium from food does not increase your risk of calcium oxalate stones. In fact, if you had calcium oxalate stones, the health care professional may tell you to have calcium every day to help prevent kidney stones and support strong bones.

Foods that are high in calcium include dairy products, such as low-fat milk and yogurt, and lactose-free milk with calcium.

Plan meals to lose weight

Studies have shown that being overweight increases your risk of kidney stones, particularly uric acid stones. A dietitian can also help you plan meals to help lose weight. Studies show that eating healthy foods that are low in carbohydrates can further increase your risk of uric acid stones and should be avoided.

Studies have shown that the Dietary Approaches to Stop Hypertension (DASH) diet can reduce the risk of kidney stones. The DASH diet is high in fruits and vegetables, moderate in low-fat dairy products, and low in animal protein. Learn more about the DASH diet.3

Can drinking water help prevent or relieve kidney stones?

Drinking enough liquid is the most important thing you can do to prevent kidney stones. Unless you have kidney failure, health care professionals recommend that you drink six to eight, 8-ounce glasses a day. People with cystine stones may need to drink even more. Talk with a health care professional about how much liquid you should drink.

References

Clinical Trials

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and other components of the National Institutes of Health (NIH) conduct and support research into many diseases and conditions.

What are clinical trials, and are they right for you?

Clinical trials are part of clinical research and at the heart of all medical advances. Clinical trials look at new ways to prevent, detect, or treat disease. Researchers also use clinical trials to look at other aspects of care, such as improving the quality of life for people with chronic illnesses. Find out if clinical trials are right for you.

What clinical trials are open?

Clinical trials that are currently open and are recruiting can be viewed at www.ClinicalTrials.gov.

Kidney Stones in Children

What is a kidney stone?

A kidney stone is a solid piece of material that forms in a kidney when substances that are normally found in the urine become highly concentrated. A stone may stay in the kidney or travel down the urinary tract. Kidney stones vary in size. A small stone may pass out of the body causing little or no pain. A larger stone may get stuck along the urinary tract and can block the flow of urine, causing severe pain or blood that can be seen in the urine.

What is the urinary tract?

The urinary tract is the body’s drainage system for removing wastes and extra water. The urinary tract includes two kidneys, two ureters, a bladder, and a urethra. The kidneys are a pair of bean-shaped organs, each about the size of a fist and located below the ribs, one on each side of the spine, toward the middle of the back. Every minute, a person’s kidneys filter about 3 ounces of blood, removing wastes and extra water. The wastes and extra water make up the 1 to 2 quarts of urine an adult produces each day. Children produce less urine each day; the amount produced depends on their age. The urine travels from the kidneys down two narrow tubes called the ureters. The urine is then stored in a balloonlike organ called the bladder. When the bladder empties, urine flows out of the body through a tube called the urethra at the bottom of the bladder.

Drawing of the urinary tract in the outline of a male, with labels for the kidneys, bladder, and ureters.
The kidneys remove wastes and extra water from the blood to form urine. Urine travels from the kidneys to the bladder through the ureters.

Are kidney stones common in children?

No exact information about the incidence of kidney stones in children is available, but many kidney specialists report seeing more children with this condition in recent years. While kidney stones are more common in adults, they do occur in infants, children, and teenagers from all races and ethnicities.

What causes kidney stones in children?

Kidney stones can form when substances in the urine—such as calcium, magnesium, oxalate, and phosphorous—become highly concentrated due to one or more causes:

  • Defects in the urinary tract may block the flow of urine and create pools of urine. In stagnant urine, stone-forming substances tend to settle together into stones. Up to one-third of children who have stones have an anatomic abnormality in their urinary tract.
  • Kidney stones may have a genetic cause. In other words, the tendency to form stones can run in families due to inherited factors.
  • An unhealthy lifestyle may make children more likely to have kidney stones. For example, drinking too little water or drinking the wrong types of fluids, such as soft drinks or drinks with caffeine, may cause substances in the urine to become too concentrated. Similarly, too much sodium, or salt, in the diet may contribute to more chemicals in the urine, causing an increase in stone formation. Some doctors believe increases in obesity rates, less active lifestyles, and diets higher in salt may be causing more children to have kidney stones.
  • Sometimes, a urinary tract infection can cause kidney stones to form. Some types of bacteria in the urinary tract break down urea—a waste product removed from the blood by the kidneys—into substances that form stones.
  • Some children have metabolic disorders that lead to kidney stones. Metabolism is the way the body uses digested food for energy, including the process of breaking down food, using food’s nutrients in the body, and removing the wastes that remain. The most common metabolic disorder that causes kidney stones in children is hypercalciuria, which causes extra calcium to collect in the urine. Other more rare metabolic conditions involve problems breaking down oxalate, a substance made in the body and found in some foods. These conditions include hyperoxaluria, too much oxalate in the urine, and oxalosis, characterized by deposits of oxalate and calcium in the body’s tissues. Another rare metabolic condition called cystinuria can cause kidney stones. Cystinuria is an excess of the amino acid cystine in the urine. Amino acids are the building blocks of proteins.

What are the signs and symptoms of kidney stones in children?

Children with kidney stones may have pain while urinating, see blood in the urine, or feel a sharp pain in the back or lower abdomen. The pain may last for a short or long time. Children may experience nausea and vomiting with the pain. However, children who have small stones that pass easily through the urinary tract may not have symptoms at all.

What types of kidney stones occur in children?

Four major types of kidney stones occur in children:

  • Calcium stones are the most common type of kidney stone and occur in two major forms: calcium oxalate and calcium phosphate. Calcium oxalate stones are more common. Calcium oxalate stone formation has various causes, which may include high calcium excretion, high oxalate excretion, or acidic urine. Calcium phosphate stones are caused by alkaline urine.
  • Uric acid stones form when the urine is persistently acidic. A diet rich in purines—substances found in animal proteins such as meats, fish, and shellfish—may cause uric acid. If uric acid becomes concentrated in the urine, it can settle and form a stone by itself or along with calcium.
  • Struvite stones result from kidney infections. Eliminating infected stones from the urinary tract and staying infectionfree can prevent more struvite stones.
  • Cystine stones result from a genetic disorder that causes cystine to leak through the kidneys and into the urine in high concentration, forming crystals that tend to accumulate into stones.

How are kidney stones in children diagnosed?

The process of diagnosing any illness begins with consideration of the symptoms. Pain or bloody urine may be the first symptom. Urine, blood, and imaging tests will help determine whether symptoms are caused by a stone. Urine tests can be used to check for infection and for substances that form stones. Blood tests can be used to check for biochemical problems that can lead to kidney stones. Various imaging techniques can be used to locate the stone:

  • Ultrasound uses a device, called a transducer, that bounces safe, painless sound waves off organs to create an image of their structure. An abdominal ultrasound can create images of the entire urinary tract. The procedure is performed in a health care provider’s office, outpatient center, or hospital by a specially trained technician, and the images are interpreted by a radiologist—a doctor who specializes in medical imaging; anesthesia is not needed. The images can show the location of any stones. This test does not expose children to radiation, unlike some other imaging tests. Although other tests are more useful in detecting very small stones or stones in the lower portion of the ureter, ultrasound is considered by many health care providers to be the best screening test to look for stones.
  • Computerized tomography (CT) scans use a combination of x-rays and computer technology to create threedimensional (3-D) images. A CT scan may include the injection of a special dye, called contrast medium. CT scans require the child to lie on a table that slides into a tunnel-shaped device where the x-rays are taken. The procedure is performed in an outpatient center or hospital by an x-ray technician, and the images are interpreted by a radiologist; anesthesia is not needed. CT scans may be required to get an accurate stone count when children are being considered for urologic surgery. Because CT scans expose children to a moderate amount of radiation, health care providers try to reduce radiation exposure in children by avoiding repeated CT scans, restricting the area scanned as much as possible, and using the lowest radiation dose that will provide the needed diagnostic information.
  • X-ray machines use radiation to create images of the child’s urinary tract. The images can be taken at an outpatient center or hospital by an x-ray technician, and the images are interpreted by a radiologist; anesthesia is not needed. The x-rays are used to locate many kinds of stones. A conventional x-ray is generally less informative than an ultrasound or CT scan, but it is less expensive and can be done more quickly than other imaging procedures.

How are kidney stones in children treated?

The treatment for a kidney stone usually depends on its size and what it is made of, as well as whether it is causing symptoms of pain or obstructing the urinary tract. Small stones usually pass through the urinary tract without treatment. Still, children will often require pain control and encouragement to drink lots of fluids to help move the stone along. Pain control may consist of oral or intravenous (IV) medication, depending on the duration and severity of the pain. IV fluids may be needed if the child becomes dehydrated from vomiting or an inability to drink. A child with a larger stone, or one that blocks urine flow and causes great pain, may need to be hospitalized for more urgent treatment. Hospital treatments may include the following:

  • Shock wave lithotripsy (SWL). A machine called a lithotripter is used by the doctor to crush the kidney stone. In SWL, the child lies on a table or, less commonly, in a tub of water above the lithotripter. The lithotripter generates shock waves that pass through the child’s body to break the kidney stone into smaller particles to pass more readily through the urinary tract. Children younger than age 12 may receive general anesthesia during the procedure. Older children usually receive an IV sedative and pain medication.
  • Removal of the stone with a ureteroscope. A ureteroscope is a long, tubelike instrument used to visualize the urinary tract. After the child receives a sedative, the doctor inserts the ureteroscope into the child’s urethra and slides the scope through the bladder and into the ureter. Through the ureteroscope, which has a small basket attached to the end, the doctor may be able to see and remove the stone in the ureter.
    Drawing of ureteroscopic stone removal. A long scope, labeled ureteroscope, is inserted through the bladder into the ureter, where a stone is blocking the flow of urine. An inset picture shows an enlarged cross-section of the ureter in which a wire basket at the end of the ureteroscope has captured the stone for removal; the ureter, stone, and ureteroscope are labeled. In the larger picture, the kidney, ureter, stone, bladder, ureteroscope, and eye piece are labeled.
    Ureteroscopic stone removal
  • Lithotripsy with a ureteroscope. Another way to treat a kidney stone through a ureteroscope is to extend a flexible fiber through the scope up to the stone. The fiber is attached to a laser generator. Instead of shock waves, the fiber delivers a laser beam to break the stone into smaller pieces that can pass out of the body in the urine. The child may receive general anesthesia or IV sedation.
    Drawing of a percutaneous nephrolithotomy. A kidney with an internal stone is shown in cross-section. A thin wire labeled nephroscope is inserted through the skin into the kidney to locate the stone. A slightly thicker probe labeled ultrasonic probe is also inserted through the skin into the kidney to deliver sound waves that will break up the kidney stone.
    Percutaneous nephrolithotomy
  • Percutaneous nephrolithotomy. In this procedure, a tube is inserted directly into the kidney through an incision in the child’s back. Using a wire-thin viewing instrument called a nephroscope, the doctor locates and removes the stone. For large stones, an ultrasonic probe that acts as a lithotripter may be needed to deliver shock waves that break the stone into small pieces that can be removed more easily. Children receive general anesthesia for percutaneous nephrolithotomy. Often, children stay in the hospital for several days after the procedure and may have a small tube called a nephrostomy tube inserted through the skin into the kidney. The nephrostomy tube drains urine and any residual stone fragments from the kidney into a urine collection bag. The tube usually is left in the kidney for 2 or 3 days while the child remains in the hospital.
    Drawing of a nephrostomy tube with the kidney, nephrostomy tube, and urine collection bag labeled. Two kidneys are shown within the outline of a female torso and pelvis. The curled end of the nephrostomy tube is placed within the left kidney. The nephrostomy tube exits the body through the skin. A urine collection bag is connected to the external end of the nephrostomy tube.
    Nephrostomy tube

How are kidney stones in children prevented?

To prevent kidney stones, health care providers and their patients must understand what is causing the stones to form. Especially in children with suspected metabolic abnormalities or with recurrent stones, a 24-hour urine collection is obtained to measure daily urine volume and to determine if any underlying mineral abnormality is making a child more likely to form stones. Based on the analysis of the collected urine, the treatment can be individualized to address a metabolic problem.

In all circumstances, children should drink plenty of fluids to keep the urine diluted and flush away substances that could form kidney stones. Urine should be almost clear.

Eating, Diet, and Nutrition

Families may benefit from meeting with a dietitian to learn how dietary management can help in preventing stones. Depending on the underlying cause of the stone formation, medications may be necessary to prevent recurrent stones. Dietary changes and medications may be required for a long term or, quite often, for life. Some common changes include the following:

  • Children who tend to make calcium oxalate stones or have hypercalciuria should eat a regular amount of dietary calcium and limit salt intake. A thiazide diuretic medication may be given to some children to reduce the amount of calcium leaking into the urine.
  • Children who have large amounts of oxalate in the urine may need to limit foods high in oxalate, such as chocolate, peanut butter, and dark-colored soft drinks.
  • Children who form uric acid or cystine stones may need extra potassium citrate or potassium carbonate in the form of a pill or liquid medication. Avoiding foods high in purines—such as meat, fish, and shellfish—may also help prevent uric acid stones.

Points to Remember

  • A kidney stone is a solid piece of material that forms in a kidney when some substances that are normally found in the urine become highly concentrated.
  • Kidney stones occur in infants, children, and teenagers from all races and ethnicities.
  • Kidney stones in children are diagnosed using a combination of urine, blood, and imaging tests.
  • The treatment for a kidney stone usually depends on its size and composition as well as whether it is causing symptoms of pain or obstructing the urinary tract.
  • Small stones usually pass through the urinary tract without treatment. Still, children will often require pain control and encouragement to drink lots of fluids to help move the stone along.
  • Children with larger stones, or stones that block urine flow and cause great pain, may need to be hospitalized for more urgent treatment.
  • Hospital treatments may include shock wave lithotripsy (SWL), removal of the stone with a ureteroscope, lithotripsy with a ureteroscope, or percutaneous nephrolithotomy.
  • To prevent recurrent kidney stones, health care providers and their patients must understand what is causing the stones to form.
  • In all circumstances, children should drink plenty of fluids to keep the urine diluted and flush away substances that could form kidney stones. Urine should be almost clear.

Clinical Trials

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and other components of the National Institutes of Health (NIH) conduct and support research into many diseases and conditions.

What are clinical trials, and are they right for you?

Clinical trials are part of clinical research and at the heart of all medical advances. Clinical trials look at new ways to prevent, detect, or treat disease. Researchers also use clinical trials to look at other aspects of care, such as improving the quality of life for people with chronic illnesses. Find out if clinical trials are right for you.

What clinical trials are open?

Clinical trials that are currently open and are recruiting can be viewed at www.ClinicalTrials.gov.

September 2016
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This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. The NIDDK translates and disseminates research findings through its clearinghouses and education programs to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by the NIDDK is carefully reviewed by NIDDK scientists and other experts.