Kidney Stones: Causes, Symptoms & Treatment

kidney stones form when there is not enough liquid to dilute waste chemicals in urine
Kidney stones are hard masses that form in the kidneys when there is not enough liquid to dilute waste chemicals in the urine.
Credit: remik44992 | Shutterstock

A kidney stone is a hard mass that forms in the kidneys from minerals in the urine, and if large enough, can cause serve pain.


Kidney stones form when there is not enough liquid in the urine to dilute out waste chemicals, such as calcium, oxalate and phosphorous. These waste chemicals become concentrated, and crystals begin to form, according to the National Kidney Foundation.

Kidney stones can vary in size, with some as small as a grain of sand, and others as large as a pearl or even a golf ball, according to the National Institutes of Health.

Small stones may pass down the urinary tract and be excreted without causing symptoms. Larger stones may get stuck in the urinary track and block the flow of urine, which can cause severe pain or bleeding, the NIH says.

In the United States, kidney stones send more than 300,000 people to the emergency room each year, the NIH says.



Symptoms of kidney stones include pain while urinating, blood in the urine and sharp pain in the lower back or lower abdomen, according to the NIH. People who think they have a kidney stone, or who have serious symptoms such as extreme pain that won't go away, fever and chills, and vomiting, should see their doctor.

Risk factors

People are at increased risk for kidney stones if they've had a stone in the past, or a member of their family has had a stone. The most common time to develop kidney stones is between ages 20 and 50 years old, according to the National Kidney Foundation.

Other risk factors include not drinking enough water, eating a diet high in protein, sodium and sugar, being obese, or undergoing gastric bypass surgery, according to the Mayo Clinic.

Kidney stones after lithotripsy
Kidney stones broken into smaller pieces after lithotripsy.
Credit: Atelier_A | Shutterstock


Small kidney stones don't usually need treatment, but an individual may need to take pain medication, according to the NIH. Patients with kidney stones should also drink lots of fluids, which can help the stone to pass.

Large kidney stones, or stones blocking the urinary tract, may need other treatments. One treatment is called shock wave lithotripsy, during which a doctor uses a machine the produces shock waves to break the stone into small pieces so it can pass through the urinary tract.

Another treatment, called ureteroscopy, uses a special tool called a ureteroscope to view the kidney stone in the ureter — the tube that connects the kidneys to the bladder. A doctor can then remove the stone or use laser energy to break it.


The best way to prevent most types of kidney stones is to drink lots of fluids (about 2 to 3 liters, or 0.5 to 0.8 gallons, each day), according to the NIH.

Determining the type of stone you had — by catching the stone as it passes and having it analyzed by a lab — can help doctors understand what caused the stone, and make recommendations to prevent the condition.

For people who've had stones made of calcium oxalate, doctors may recommend that they avoid foods high in oxalate, such as spinach, rhubarb, nuts and wheat bran, the NIH says. Reducing salt intake may also reduce a person's risk of kidney stones.

While some stones are made of calcium, eating calcium rich foods doesn't affect your risk of kidney stones, according to the Mayo Clinic.

Information on this page should not be construed as medical advice nor an attempt to make diagnoses. Anyone who thinks they may have a kidney stone or other medical condition should seek medical attention.

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Rachael Rettner, MyHealthNewsDaily Staff Writer

Rachael Rettner

Rachael has been with Live Science since 2010. She has a masters degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a Bachelor of Science in molecular biology and a Master of Science in biology from the University of California, San Diego. Follow Rachael on Twitter and Google+.
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