What are kidney stones?

Kidney stones are small hard objects that form from minerals found in your urine. Normally, your body disposes of these minerals through urination. However, sometimes there are too much of these substances, and too little water to carry them away. When this happens, crystals start to form. These objects attract other substances in the kidneys, causing them to grow.
At some point, the stone passes in the urine. Sometimes they pass without much pain, but other times, they cause a lot of pain because they get stuck in the tube between the kidneys and bladder. Kidney stones usually pass in a few days to a few weeks depending on their size.
About 500,000 people in the United States seek medical attention for kidney stones each year. Men are about twice as likely as women to get a kidney stone.
Signs of kidney stones
Symptoms of kidney stones include:
- More frequent urination
- Sharp pain in your lower back, side, abdomen, or groin
- Inability to urinate
- Bad smelling urine
- Burning when urinating
- Blood in urine
- Intense need to urinate
- Dark urine
- Nausea
- Vomiting
- Pain at the tip of the penis (in men)
Types of kidney stones
Four minerals may form kidney stones. Doctors treat each type of kidney stone in the same way. The types of kidney stones are:
- Calcium oxalate
- Uric acid
- Struvite
- Cystine
Causes of kidney stones
Higher levels of the previously mentioned minerals in the urine cause kidney stones. Some lifestyle factors can affect the levels of these substances in your urine. Eating less of these foods can help reduce your chances of kidney stones:
- Meat
- Dairy products
- Eggs
- Nuts
- Spinach
- Wheat bran
- Rhubarb
- Sodium
Doctors also recommend making sure that you drink 48 to 64 ounces of water per day to reduce the risk of kidney stones.
When to see the doctor for kidney stones
Some kidney stones pass on their own without medical intervention. However, you should see a doctor if your pain is accompanied by:
Additionally, if you have only one kidney, you should seek medical intervention for your kidney stone. Also, if you’ve been trying to pass your stone for close to six weeks, seek medical attention.

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Kidney Stone Crystal Browse through our medical image collection to see and discover unique diseases and conditions See ImagesDiagnosing kidney stones
If you have symptoms of a kidney stone, doctors may take an X-ray, ultrasound, or computerized tomography scan (CT scan) to diagnose you.
People who have asymptomatic kidney stones may get a surprise diagnosis if they have an abdominal x-ray for another reason.
Treatments for kidney stones
The treatment of kidney stones depends on your particular situation.
Doctors may prescribe pain medication and tell you to drink plenty of water if they think you can pass the stone on your own. It can take anywhere from a few days to several weeks for the stone to pass.
When you do pass it, they may ask you to collect it so they can test it to find out what type of stone it is.
If the pain is causing you to vomit, you may become dehydrated and require intravenous hydration.
If the stone is blocking your ureter or causing you extreme pain, there are other treatment options:
- Shock wave lithotripsy: Doctors use sound waves to break up large kidney stones into smaller pieces.
- Cystoscopy: Doctors use a device to see inside the urinary system to find the kidney stone. They can then remove it.
- Ureteroscopy: Similar to cystoscopy, except it is a more long and thin instrument.
- Percutaneous nephrolithotomy: During this procedure, doctors make a small incision in your back to access your kidney. They then remove the stone straight from the kidney.
National Institute of Diabetes and Digestive and Kidney Diseases: "Symptoms and Causes of Kidney Stones."
National Institute of Diabetes and Digestive and Kidney Diseases: "Treatment for Kidney Stones."
National Kidney Foundation: "Kidney Stones."
Urology Care Foundation: "Kidney Stones."
Washington University School of Medicine in St. Louis: "Kidney Stones Overview."
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