What Are Kidney Stones?

A kidney stone isn’t actually made of stone. But if you have to pass one when you pee, it may feel like it is.

Kidney stones are small -- usually between the size of a kernel of corn and a grain of salt. When your body has too much of certain minerals, and at the same time doesn’t have enough liquid, these pebble-like objects can form.

The stones can be brown or yellow, and smooth or rough. Both men and women can get kidney stones, but men’s chances of getting them are about double that of women’s.


It’s often hard to figure out the reason you got a kidney stone. But they are created when your urine has high levels of certain minerals. These include:

Think about stirring up your favorite drink from a powder mix. If you don’t add enough liquid -- say, water or juice -- the powder will clump up and turn into hard, dry chunks.

Similarly, if you don’t have enough urine in your body to water down the high concentration of minerals, stones can form.

Other things that can make you more likely to get kidney stones include:


Doctors break down kidney stones into types, and it’s important because which kind you have could affect the treatment you get. They include:

Calcium stones: These are the most common ones. Even just eating some foods very high in oxalates, such as rhubarb, or taking unusually high levels of Vitamin D, can boost your chances of getting this type. You could get this kind if you typically don’t drink enough water or if you sweat a lot and don’t replace the fluids you lose.

Cystine stones: This is the least common type. Once you get a cystine stone, there is a chance that you may have one again. You inherit the possibility of getting them from your parents, both of whom would have to have the same type of genetic mutation.

Struvite stones: Infections, especially in the urinary tract, can cause you to have this kind of stone.

Uric acid stones: Eating large amounts of animal proteins can cause uric acid to build up in the urine and eventually form a stone either with or without calcium. Risk factors include gout, diabetes, and chronic diarrhea.



Even if you have a kidney stone, you may not have any symptoms -- that is, until the stone goes on the move.

The stone can move around within the kidney, or into the tube that connects your kidney to your bladder. Symptoms can vary and can range in severity. They include:

  • Pain in your side or back, below the ribs, which is severe
  • Pain in your groin and lower abdomen
  • Pain that comes and goes and ranges in severity
  • Painful urination and going more often than you usually do
  • Urine that is cloudy, pink, red, or brown, or that has a bad smell
  • Feeling like you need to pee all the time
  • Fever and chills if you have an infection
  • Small amounts of urine when you do go

When to Call a Doctor

If you are in really bad pain, you probably want to see a doctor. Other signs you should quickly seek medical care include:

  • Being sick to your stomach and throwing up, while in pain
  • Being feverish and cold off and on, while in pain
  • Having bloody urine or a hard time going


How does your doctor know if you really do have a kidney stone?

First, she will get a medical history and examine you.

Then, if needed, she will order tests to get pictures of your kidneys and urinary tract.

Once you have passed the stone, the doctor will have it analyzed to figure out what it was made of. You also might need to collect your pee for 24 hours to have it tested.

All of these results will help the doctor figure out how best to treat you.


If your kidney stone is small, you may be able to get rid of it when you pee.

Your doctor may want you to save the stone so it can be tested. If she can figure out what kind of stone it is, that may help prevent you from having another one.

If your stone is bigger or you can’t pass it, you might be in a fair amount of pain. In this case, the doctor can break up the stone in a couple of ways, so your body can eventually get rid of it. These include:


Shock wave lithotripsy: This is the most common procedure for kidney stones in the United States. It uses shock waves, which can blast the stone into little pieces. Then, the smaller pieces can more easily be passed in your urine.

The treatment takes about an hour, and you can usually go home about an hour later.

This treatment doesn’t involve any surgical cuts, but there’s still some pain. Your doctor will talk over your options with you: sedation, local anesthesia (you’re given something to numb the pain but stay awake), general anesthesia (you’re not awake during the procedure).

Ureteroscopy: This procedure treats stones in the kidneys and ureters. Your doctor uses a thin, flexible scope to find and remove stones. No cuts are made in your skin. You'll sleep through this procedure.

Your doctor will pass the scope through your bladder and ureter into your kidney. She uses a small basket to remove small stones. If the stones are larger, the doctor will pass a laser through the scope to break them up. Typically, you are able to go home on the same day.

Surgery: Another way doctors can get rid of a kidney stone is to cut a small hole in your back and through your kidney in order to remove the stone. If this procedure is done, you could have to stay in the hospital for several days.


If you get a kidney stone, you are in danger of getting more later in life. About half of people will get another one within 7 years of their first one if they don’t take care to try to prevent it.

To stop this from happening, try the following:

Drink plenty of water: You should drink at least 64 ounces of water each day. Some of that liquid can be orange juice, lemonade, or limeade.

Cut back on sodium and salty foods: Lots of sodium can raise calcium levels in your urine. And that can cause stones to form. If you cut back on the sodium you get from food and beverages, it also will help your heart and lower your blood pressure.


Drink and eat enough calcium: This preventive step might sound a little confusing, as doctors will tell you that high calcium levels (because of too much sodium) in your urine can cause a stone.

But not taking in enough calcium can boost the level of the oxalates in your urine. It’s found in other food beside rhubarb, including spinach, beets, bran flakes, potato chips, and French fries. And oxalates can cause kidney stones.

It’s best to get your calcium from foods and beverages rather than supplements.

Avoid certain foods and soft drinks: If you have already had at least one kidney stone, it’s a good idea to limit the animal protein you eat each day to a piece about the size of a deck of cards. Some foods, such as eggs, spinach, beets, chocolate, and nuts, as well as colas, have been linked to kidney stones.

WebMD Medical Reference Reviewed by Minesh Khatri, MD on December 23, 2018



National Institute of Diabetes and Digestive and Kidney Diseases: “Kidney Stones in Adults.”

National Kidney Foundation: “Kidney Stones.”

The Mayo Clinic: “Diseases and Conditions: Kidney Stones.”

Urology Care Foundation, The Official Foundation of the American Urological Association: “What are Kidney Stones?”

Harvard Health Publications, Harvard Medical School: “5 steps for preventing kidney stones.”

University of Chicago: “Types of Kidney Stones: A Primer.”

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