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 in your 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 urethra).
When a stone travels through a ureter, it usually causes pain and other symptoms.
What causes kidney stones?
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.
Kidney stones 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 future.
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 another disease.
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 pass.
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.
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Kidney stones 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 kidney stones.
- 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.
In rare 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.
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 the urethra, which leads outside the body), their movement may cause:
- 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 vomiting.
- Blood in the urine (hematuria), which can occur either with stones that stay in the kidney or with those that travel through the ureters.
- 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 include appendicitis, hernias, ectopic pregnancy, and prostatitis.
A 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.
Most 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 stones.
Problems that may occur with kidney stones include:
- An increased risk of urinary tract infection, or making an existing urinary tract infection worse.
- 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 longer.
Kidney stones are more serious for people who have a single kidney or an impaired immune system or have had a kidney transplant.
Stones in pregnant women
When stones occur during pregnancy, an obstetrician and 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.
- Being overweight. This can cause both insulin resistance and increased calcium in the urine, which can result in a greater risk for kidney stones.
- Medicine. Some medicines, such as acetazolamide (Diamox) and indinavir (Crixivan), can cause kidney stones to form.
Risk factors you cannot control
Things you can't control include:
- Age and gender.
- A family history of kidney stones.
- A personal history of frequenturinary tract infections.
- Other diseases or conditions, such as Crohn's disease, hyperparathyroidism, or gout.
- Intestinal surgery or gastric bypass surgery.
- Insulin resistance, which can occur because of diabetes or obesity.
When should you call your doctor?
Call a doctor immediately if you have symptoms that suggest you have a kidney stone, such as:
- Severe pain in your side, abdomen, groin, or genitals. It may get worse in waves.
- Blood in your urine.
- Signs of a urinary tract infection, such as pain or burning when you urinate.
Call your doctor if you have been diagnosed with a kidney stone and have another problem, such as:
- Severe nausea or vomiting.
- Fever and chills.
- Severe pain in your side in the area of your kidney (flank pain).
Call your doctor to find out if you need an exam when you:
- Have been diagnosed with a kidney stone, and you need a stronger pain medicine.
- Pass a stone, even if there was little or no pain. Save the stone, and ask your doctor whether it should be tested.
Watchful waiting is a wait-and-see approach. If you get better on your own, you won't need medical treatment. If you get worse, you and your doctor will decide what to do next.
If you are passing a kidney stone under your doctor's advice, you may be able to pass the stone without medical treatment if you:
- Can control your pain with medicine.
- Know how to look for and collect kidney stones you pass.
- Do not have signs of infection, such as fever and chills.
- Are able to drink plenty of fluids.
- Do not have severe nausea or vomiting.
Who to see
If you need immediate help because of pain from kidney stones, you may see an emergency medicine specialist.
Health professionals who can diagnose and treat nonurgent kidney stones include:
Exams and Tests
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 urinary tract.
- A noncontrast spiral computed tomography (CT) scan is a special type of CT scan that moves in a circle.
- An ultrasound exam (ultrasonogram) uses reflected sound waves to produce a picture of your urinary tract.
- An intravenous pyelogram (IVP) is an X-ray test that shows pictures of the urinary tract, including any kidney stones.
- A retrograde pyelogram uses a dye to find out whether a kidney stone or something else is blocking your urinary tract.
- Urinalysis and urine cultures test your urine.
- An abdominal X-ray (KUB) gives a picture of the kidneys, the bladder, and the tubes that connect the kidneys to the bladder (ureters).
Tests to find out the type of stone
Finding out the type of your kidney stone will help with treatment decisions and measures to prevent stones from forming again. Tests you may have include:
- A medical history and physical exam.
- 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 is.
- 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 needed.
- 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 the stone. 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.
Preventing future stones
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 forming.
What to think about
You may need more treatment for your kidney stones if you have continuing problems and:
- A lot of urinary tract infections.
- Decreased kidney function.
- A single kidney.
- An impaired immune system.
- Have had a kidney transplant.
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 drink.
- 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 another stone.
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 kidney stone.
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.
Medicine to help pass stones
Medicine you can buy without a prescription, such as nonsteroidal anti-inflammatory drugs (NSAIDs), may relieve your pain while you pass a stone.
Your doctor may also prescribe medicine to help your body pass the stone, such as alpha-blockers.
Medicine to prevent stones
Which medicine you take depends on the type of stones you have.
Calcium stones are the most common kind of kidney stone. To prevent them, you may take:
- Potassium citrate.
Uric acid stones
Some kidney stones are made of uric acid, a waste product that normally exits the body in the urine. To prevent these types of stones, you may take:
- Potassium citrate.
- Sodium bicarbonate.
A very small number of stones are made of a chemical called cystine. Medicines to prevent them include:
- Potassium citrate.
Some struvite stones (staghorn calculi) form because of frequent 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 percutaneous nephrolithotomy or nephrolithotripsy, the surgeon makes a small cut in your back. He or she then puts a hollow tube into your kidney and either removes (lithotomy) or breaks up and removes (lithotripsy) the stone. This surgery may be used if other procedures do not work or if you have a very large stone.
- 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:
- Extracorporeal shock wave lithotripsy (ESWL). ESWL uses shock waves that pass easily through the body but are strong enough to break up a kidney stone. This is the most commonly used medical procedure for treating kidney stones.
- Ureteroscopy. The surgeon passes a very thin viewing tool (ureteroscope) up the urinary tract to the stone's location, and then he or she uses tools to remove the stone or break it up for easier removal. You may need a small, hollow tube (ureteral stent) placed in the ureter to keep it open for a short time and drain urine and any stone pieces. This procedure is often used for stones that have moved from the kidney to the ureter.
Whether these treatments will work for you will depend on the size of the stone, its location in the urinary tract, and your overall health.
Other Works Consulted
- Agency for Healthcare Research and Quality (2012). Recurrent Nephrolithiasis in Adults: Comparative Effectiveness of Preventive Medical Strategies (AHRQ Publication No. 12-EHC049-EF). Rockville, MD: Agency for Healthcare Research and Quality. Also available online: http://effectivehealthcare.ahrq.gov/ehc/products/274/1035/kidney-stones-prevention-report-130409.pdf.
- American Urological Association and European Association of Urology (2007, reaffirmed 2010). Ureteral Calculi: 2007 Guideline for the Management of Ureteral Calculi. Available online: http://www.auanet.org/content/guidelines-and-quality-care/clinical-guidelines.cfm?sub=uc.
- Ferrandino MN, et al. (2012). Evaluation and medical management of urinary lithiasis. In AJ Wein et al., eds., Campbell-Walsh Urology, 10th ed., vol. 2, pp. 1287–1323. Philadelphia: Saunders.
- Smith-Bindman R, et al. (2014). Ultrasonography versus computer tomography for suspected nephrolithiasis. New England Journal of Medicine, 371(12): 1100–1110. DOI: 10.1056/NEJMoa1404446. Accessed November 17, 2014.
- Stoller ML (2013). Urinary stone disease. In JW McAninch, TF Lue, eds., Smith and Tanagho's General Urology, 18th ed., pp. 249–279. New York: McGraw-Hill.
- Tseng TY, Preminger GM (2015). Kidney stones: Flexible ureteroscopy. BMJ Clinical Evidence. http://clinicalevidence.bmj.com/x/systematic-review/2003/overview.html. Accessed April 14, 2016.