A kidney stone is a solid piece of material that forms in a kidney when there are high levels of certain substances in the urine. These substances are normally found in the urine and do not cause problems at lower levels.
A stone may stay in the kidney or travel down the urinary tract. Kidney stones vary in size. A small stone may pass on its own, causing little or no pain. A larger stone may get stuck along the urinary tract. A stone that gets stuck can block the flow of urine, causing severe pain or bleeding.
What causes kidney stones?
Kidney stones are caused by high levels of calcium, oxalate, and phosphorus in the urine. Some foods may cause kidney stones in certain people. You may be more likely to get a kidney stone if you have
- a condition that affects levels of substances in your urine that can cause stones to form
- a family history of kidney stones
- repeating, or recurrent, urinary tract infections
- blockage of your urinary tract
- digestive problems
You may also be more likely to get a kidney stone if you don’t drink enough fluids or if you take certain medicines.
What are the symptoms of kidney stones?
You may have a kidney stone if you
- have pain while urinating
- see blood in your urine
- feel a sharp pain in your back or lower abdomen—the area between your chest and hips
The pain may last for a short or long time. You may have nausea and vomiting with the pain.
If you have a small stone that passes on its own easily, you may not have symptoms at all.
When should I call a doctor?
You should call a doctor if you have any of the following:
- extreme pain in your back or lower abdomen that won’t go away
- blood in your urine
- fever and chills
- urine that smells bad or looks cloudy
- pain when you urinate
These problems may mean you have a kidney stone or a more serious condition.