Kidney Stones: Causes, symptoms and treatment options

What are kidney stones?

Your kidneys are a filter system for your body. They remove waste like extra salt, water, potassium, acid and nitrogen from your blood and produce urine (pee). Sometimes, there can be too many of these substances in the blood and your kidneys cannot filter it all out.  When these substances build up, they can form crystals in your kidneys, and these crystals can attract one another to form a solid object called a kidney stone.  

Kidney stones vary in size and shape. They can be as small as a grain of sand or as large as a golf ball. Kidney stones can be either smooth or jagged on the edges. If a kidney stone is not passed or removed from your body, it can continue to grow.  

Some kidney stones can become too large to leave your body through your urine. When this happens, you may need surgery to break the stone into smaller pieces or to remove it.  

It is common to have multiple kidney stones throughout your life; most people who have a kidney stone will form another one later.  

Note: Some medicines can cause kidney stones to form. Talk to your doctor about the medicines you are currently taking and if you are at risk for forming kidney stones. 

What are the different types of kidney stones? 

There are five types of kidney stones: 

1. Calcium stones 

Calcium stones are the most common type of kidney stone, they make up 4 out of 5 cases of kidney stones in the United States. There are two kinds of calcium stones: 

• calcium oxalate stones, which are most calcium stones 
• calcium phosphate stones 

Calcium stones do not form from the calcium that you eat. They form when your bones do not use up all of the calcium in your body, and your kidneys get rid of this extra calcium.  

2. Uric stones 

Uric stones are another common type of kidney stone, they make up 1 in 10 of all kidney stones in the United States. Uric acid can result from high levels of a natural chemical called purine, which is turned into uric acid in the body. Purine is found in some meats and shellfish, and eating foods that are high in purine can increase the amount of uric acid in your body. Uric stones form when there is too much uric acid in your urine. Some other common causes of too much uric acid in your urine include type 2 diabetes, obesity, and metabolic syndrome. Issues with breaking down uric acid can be inherited (passed down in families), so your family may have a history of these types of kidney stones.  

3. Struvite stones 

Struvite stones, also known as "infection stones," are less common than calcium and uric stones. In the United States, 5% to 15% of all stones are struvite stones. These stones form from the effect of urease, a chemical produced by bacteria that cause urinary tract infections (UTIs). They are more common in women than men, and in people who have a urinary catheter. A urinary catheter is a flexible tube, inserted into your bladder by a doctor or nurse, used to empty your bladder when you are having problems peeing naturally. Struvite stones grow fast, and as a result, they can grow large enough to fill the kidney, which is called a staghorn stone. When doctors treat struvite stones, it is also important to treat the urinary tract infection that caused the stones to form.  

4. Cystine stones  

Cystine stones are caused by a rare condition called cystinuria that is passed down in families. They account for 1 out of 10 adult kidney stones and about 7 out of 10  pediatric kidney stones. Cystinuria causes a natural chemical called cystine to leak into your urine. Cystine does not dissolve easily in the urine, and when there is too much cystine, kidney stones can form. Most people with cystinuria will form their first stone sometime in childhood. They will then go on to form many stones throughout their life. This condition can be treated, but not cured. Visit National Organization for Rare Disease (NORD) to learn more about cystinuria.  

 5. Staghorn Stones  

Staghorn stones are not differentiated by their chemical makeup, but rather by their size and shape. They are typically a type of struvite stone, but they can also be composed of calcium, uric acid or cystine. Staghorn stones are stones that grow large enough to fill multiple branches of your kidney. They can cause kidney damage and should be taken out as quickly as possible.  

What are the risk factors for kidney stones? 

Anyone can get a kidney stone, but some people are more likely than others to get them. Men get kidney stones more often than women. Kidney stones are also more common in non-Hispanic white people than in people of other ethnicities. Some rare genetic diseases may cause kidney stones (such as primary hyperoxaluria(PH1) and cystinuria). 

You may be more likely to get a kidney stone if you:  

• Have had kidney stones before  
• Have a family member who has had kidney stones 
• Do not drink enough water; especially if you are an athlete 
• Have a job that exposes you to high heat outside  
• Do not pee when you feel the need to  
• Eat a lot of protein, sodium (salt), or sugar 
• Are overweight or obese  
• Have diabetes  
• Have had gastric bypass surgery 
• Have polycystic kidney disease 
• Have a health problem that causes your urine (pee) to contain high levels of cystine, oxalate, uric acid or calcium 
• Have a health problem with your digestive system 
• Have arthritis in your joints from gout 
• Take certain medicines, such as calcium-based antacids 
• Have a genetic condition that can cause stones to form (such as PH1or cystinuria) 

Kidney stones can develop at any age, but if your child or a teen has kidney stones, make sure to talk with their doctor about additional testing to understand the cause of their kidney stones. Forming stones at a young age can be an indicator of an underlying condition.  

What are the symptoms of kidney stones? 

If you have a small kidney stone, it may travel out of your body through your urinary tract   which is the path your urine takes to leave your body. This is called passing a kidney stone. You may not have any symptoms and may never know that you had a kidney stone.  

If you have a larger kidney stone, it may get stuck in your urinary tract. Large kidney stones often can cause pain and bleeding.  

You may notice symptoms, including: 

• Blood in your urine  
• Urine that smells bad or looks cloudy  
• Constantly need to urinate  
• Pain while urinating  
• Sharp pain in your lower back, lower belly, or groin area  
• Lower back, belly, or groin pain that comes in waves and changes in intensity 
• Stomachache that does not go away 
• Feeling sick to your stomach or throwing up 
• A fever and chills (this may occur when stones lead to urinary track infections (UTI's) 

You may feel a lot of pain when you pass a kidney stone or if a large kidney stone blocks the flow of your urine. 

If you are having any of these symptoms, contact your doctor. 

How are kidney stones treated? 

The treatment for a kidney stone depends on:  

• The size of the stone 
• The type of stone  
• The location of the stone 
• If the stone is causing you pain 

If your kidney stone is small and able to pass on its own, your doctor may recommend drinking lots of fluids, ideally water, to help move the stone through the urinary tract and out of your body. They may also recommend pain relief medicine to help manage any pain or discomfort from the stone.  

If your kidney stone is large or if it is blocking your urinary tract and causing pain, your doctor may recommend a treatment to break the stone into smaller pieces or to surgically remove the stone. Treatment options include: 

Lithotripsy 

Lithotripsy treatment uses shock waves to break up the kidney stone into small pieces. After the treatment, the small pieces of the kidney stone will pass through your urinary tract and out through your urine. This treatment usually takes about one hour and may be done under general anesthesia, which means you will be asleep and unable to feel the procedure. Usually, you will be able to go home the same day as the procedure.  

Ureteroscopy 

During a ureteroscopy, a doctor inserts a long tube-like tool, through the genitals and bladder, into your ureter to take out the stone (if it is small) or break the stone into small pieces (using a laser if it is large) so that it can pass through your urinary tract and out through your urine). If the stone is in your bladder, a doctor may use a cystoscope, which goes into your bladder. Both procedures are done under general anesthesia, which means you will be asleep and unable to feel the procedure and it does not usually require a hospital stay.  

Surgery 

Sometimes, the size or the location of the stone will require a more serious surgery, known as a percutaneous nephrolithotomy. This procedure involves a tube being inserted into your kidneys through a small incision in your back. This tube will help doctors locate and remove the stone. If the stone is too large, they may use a laser to break up the stone into smaller pieces. This procedure happens under anesthesia and involves a hospital stay for a few days after the procedure. 

How can I prevent kidney stones? 

It is very common to develop another kidney stone after your first one. Here are a few steps you can take to prevent forming future kidney stones:  

• Drink enough fluids, ideally water, every day. Eight to twelve cups of fluid per day is enough for most people. This is equivalent to around ¾ of a gallon of water. If you have kidney disease or need to limit your fluid intake, ask your doctor how much fluid you should have each day.  
  • It is recommended that most of the fluid you drink is water. Some fluids, like lemonade with no added sugar can be had in small amounts. Avoid drinking fluids high in sugar such as sodas and fruit juices.  
• Limit sodium (salt) and animal protein such as meat and eggs. If your doctor can find out what your kidney stone is made of, they may give you a specific eating plan to help prevent future kidney stones. 
• Take all of your prescription medicines as your doctor tells you to treat health problems that may make kidney stones more likely for you.  
• Never start or stop any new medicines or an eating plan without talking to your doctor. 

Note: Certain medicines may be prescribed to help prevent kidney stones. Talk to your healthcare team to learn more about these medicines and if they may be an option for you.  

What are the tests for kidney stones? 

There are different kinds of tests your doctor can do to find out the size and type of stone that you have. These results can help your doctors decide the best way to treat your stones and how you can prevent future stones. Ask your doctor about the different types of and what they recommend for you. 

Urine test: your doctor may test your urine to understand the different kinds of substances that are in your urine which could include uric acid, cystine, oxalate and calcium. This can help your healthcare team understand what medicines to give you, and what you can do to prevent future stones.  

24 Hour urine test: you may be asked to collect your urine for 24 hours. This test allows your doctor to check for crystal forming substances, your creatinine level, and the pH of your urine. All of these are factors in the formation of kidney stones. You will likely be prescribed a kit from your provider with a large container to put your pee in, and a plastic cup to catch your pee. 

• 24 hour urine test tips: 
  • Over a 24-hour period, each time you pee you will pee into a plastic cup. Then, you will pour the pee from the cup into a large container. Talk to your doctor about the best way to store the urine. They may tell you to keep it in the fridge or to keep it at room temperature. You will get specific instructions from your doctor, but in general, these are some guidelines to follow: 
    • Do not take any laxatives, acetaminophen, aspirin, allergy medicine, cough syrups or other cold medicines while collecting your urine  
    • Limit fruit, vegetables, nuts, and caffeine to one serving per day 
    • Talk to your doctor about any medicines that you take and if you should stop taking them for the collection 

It can be challenging and uncomfortable to collect and store your urine for 24 hours. Ask your doctor any questions about the test and for tips to make sure the test is as accurate as possible.  

Blood tests: similar to a urine test, your doctor may test your blood to see what substances related to stones are in your body. Elevated levels of some of these substances in your blood may mean elevated levels in your urine. 

Imaging tests: your doctor may do an ultrasound, CT, or abdominal x-ray to see where the stones are in the urinary tract and how large they are. These images will help them decide the best way to treat the stones.  

Genetic tests: some kidney stones can be caused by genetic diseases, which are passed down from parent to child. These include diseases such as primary hyperoxaluria and cystinuria, among others. If you form stones when you are young, have a history of recurring stones, or have a specific kind of stone, your doctor may recommend a genetic test. You can always ask your doctor if genetic testing is an option for you.

Stone analysis: your doctor may ask you to "catch" your passed kidney stones. This is done by urinating) through a strainer. If you don't have a strainer, pee into a cup with a paper towel or some toilet paper. Doing so will allow doctors to examine your kidney stones and find out what type of stone it is. This can help to guide treatment and prevent future kidney stones from forming.

If you frequently form kidney stones, ask your doctor about these tests. They can help you decide what kind of testing will give them the most information and how to move forward in your treatment plan.

What kind of doctor treats kidney stones? 

When you first see a doctor for your kidney stones, it will likely be a urologist. A urologist is a doctor specializing in the urinary tract, the path your urine takes to leave your body. Because kidney stones often cause pain when blocking part of your urinary tract, a urologist will help the stones pass with as little discomfort and damage as possible.  

If you are a frequent stone former, it is a good idea to ask for a referral to a nephrologist. A nephrologist is a doctor that treats the kidneys. They can see if the kidneys were damaged by stones and help small kidney stones pass through the urinary tract.  

Urologists and nephrologists often work together to identify the cause of kidney stones, help large stones pass, and prevent future stones. Ask your primary care provider for a referral to either or both kinds of providers if you have questions or concerns about your kidney stones.  

Frequently Asked Questions about Kidney Stones 

Can children get kidney stones? 

Yes, children can form kidney stones. If your child has a kidney stone, it is important to have their stones tested and to speak with a doctor to understand why a stone formed. Having kidney stones at a young age can be an indicator of a genetic disease or another underlying condition.  

Can I tell if a kidney stone is growing? 

Kidney stones do not usually cause symptoms unless they block the urinary tract. It's important to follow any prevention instructions your doctor gives you to prevent future stones from forming. If you are concerned about detecting future kidney stones, work with your doctor to form a plan. Getting an ultrasound yearly may be appropriate for frequent stone formers. 

Can I see the different kinds of stones? 

You cannot tell the difference between kidney stones with your eyes. Your doctor will use a microscope and chemical analysis to determine what kind of stone you passed. CT scans are often useful to tell calcium stones from other types. 

Can kidney stones cause kidney disease? 

Kidney stones do not typically cause kidney disease, however if they do not pass and block your urinary tract, this can cause permanent damage. Diseases such as primary hyperoxaluria can cause kidney stones but can also cause decreased kidney function or chronic kidney disease.  

Ask your doctor about steps you can take to prevent future kidney stones and if you are at risk for developing kidney disease. Together you can create a plan to keep your kidneys healthy.