Kidney Stones

Time to read 3 min


Kidney stones are small, hard deposits that form inside your kidneys. The stones are made of mineral and acid salts. They develop when your urine contains more crystal-forming substances than the fluid in your urine can dilute.

A kidney stone may not cause symptoms until it moves in your kidney or passes into the tube connecting the kidney and bladder (ureter).
Signs and symptoms may include:

  • Severe pain in the side and back, below the ribs
  • Pain that spreads to the lower abdomen and groin
  • Pain that comes in waves and fluctuates in intensity
  • Pain on urination
  • Pink, red or brown urine
  • Cloudy or foul-smelling urine
  • Nausea and vomiting
  • Persistent urge to urinate
  • Urinating more often than usual

Kidney stones form in your kidneys and can move into the ureters. Symptoms often develop or become more severe once a stone enters a ureter.


Knowing the type of kidney stone helps determine the cause and may give clues on how to reduce your risk of more stones. Often, stones form when urine becomes concentrated and minerals crystallize and stick together.

  1. Calcium stones. Most kidney stones are calcium stones, usually in the form of calcium oxalate. Oxalate is a naturally occurring substance in food. Some fruits and vegetables, as well as nuts, chocolate, and iced tea, have high oxalate levels. Your liver also produces oxalate.
  2. Struvite stones. Struvite stones form in response to an infection, such as a urinary tract infection. They can grow quickly and become quite large, sometimes with little warning.
  3. Uric acid stones. They may form in people who don’t drink enough fluids, who lose too much fluid, who eat a high-protein diet, or who have gout. Genetic factors also may increase the risk of these stones.
  4. Cystine stones. They can form in people with a hereditary disorder that causes the kidneys to excrete too much of certain amino acids.

Other stones. They include more-rare types of kidney stones.


If your doctor suspects you have a kidney stone, you may undergo one or more tests.

  • Blood tests. Blood tests may reveal too much calcium or uric acid in your blood.
  • Urine tests. A 24-hour urine collection may show that you’re excreting too many stone-forming minerals or too few stone-preventing substances.
  • Imaging tests. Imaging tests are used to identify kidney stones in your urinary tract.
  • Stone analysis. You may be asked to urinate through a strainer to catch stones you may pass. Lab analysis reveals their makeup.


Treatment for kidney stones varies, depending on the type of stone and the cause.

Conservative therapies
Most kidney stones won't require invasive treatment. The following may help pass a small stone:

  • Water. Drink as much as 2 to 3 quarts a day to flush out your urinary system. Also, stones can’t form as easily in diluted urine.
  • Pain relievers. Over-the-counter pain relievers can treat mild pain.
  • Medication. Your doctor may prescribe an alpha-blocker to relax the muscles in your ureter so that you can pass the stone more quickly and with less pain.

Invasive treatment

When conservative measures aren’t helpful, options include:

Surgery. A kidney stone is removed through a small incision in your back. Your doctor may recommend this approach if sound wave therapy is unsuccessful or the stone is very large.

Sound wave therapy. A procedure called extracorporeal shock wave lithotripsy uses sound waves to create strong vibrations (shock waves) that break the stones into tiny pieces that can be passed in your urine.

Scope procedure. To remove a smaller stone, your doctor may pass a thin, flexible tube (ureteroscope) through your urethra and bladder to your ureter. Special tools snare the stone or break it into pieces that will pass in your urine. A small tube (stent) may be placed in the ureter to relieve swelling and promote healing.


Medications can control the number of minerals and acid in your urine and may help people who form certain kinds of stones. The medication your doctor prescribes will depend on the kind of kidney stones you have. 

 Excerpt From: The Mayo Clinic. “Mayo Clinic A to Z Health Guide”. 

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