Understanding Kidney Stones


Stones With RulerKidney stones are small, hard crystals or deposits that form inside your kidneys when salts and other minerals in your urine bond together. Stones often vary in shape and size, with some growing to be quite large.  

Some stones stay in the kidneys causing little to no symptoms, and others may pass through the urinary tract, causing painful symptoms as the deposit move down the ureter (the thin tube that leads to the bladder). Some people are able to pass the stone without surgical intervention, but in some cases, surgery to remove the stone may be necessary. 



Kidney stones are common - affecting upwards of 500,000 men and women every year in the U.S. according to the American Urological Association. They come in all shapes and sizes, ranging from a grain of sand to a golf ball. Anyone who has experienced a large kidney stone knows the severe pain that can come along with one, but did you know there are different types of stones?

  1. Calcium-oxalate stones - These are the most common type of kidney stone and is typically caused by foods with salt or oxalates (byproducts of certain foods), certain medications and even your genetics.

  2. Struvite stones - These affect women more than men. These stones can grow to be very large and may occur with a kidney infection. Surgical removal of these stones is often indicated. 

  3. Uric acid stones - These stones are made of uric acid, a waste product that is passed out of the body through the urine. They may be caused by eating too much animal protein such as red meat and are more common in people with conditions such as gout and inflammatory bowel disease. 

  4. Cystine stones - These are very rare, caused by a genetic kidney disease called cystinuria.

kidney stones

Photo courtesy of: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health



Symptoms of kidney stones range from little to no pain to extreme pain and discomfort, depending on the size of the stone(s). Very small kidney stones may cause no symptoms at all and small or medium sized stones can cause minor pain. Very large stones can result in severe pain that may land you in the emergency department. 

When a kidney stone has passed into the urinary tract, symptoms may include:

  • Severe pain, usually located in the side or the back; pain may spread to the abdomen and the groin area as well
  • Urinary symptoms such as painful urination, urinary urge, and frequent need to urinate
  • Blood in the urine and/or foul smelling urine
  • Nausea and/or vomiting
  • Fever, if the stone has caused an infection

Diagnosing a Kidney Stone

Stones _singlePatients who present with symptoms of a kidney stone either in their doctor's office or in the emergency department (due to extreme pain from a large stone) will have one of several diagnostic tests performed to confirm the diagnosis. For large kidney stones, tests most commonly performed include: CT scan, Ultrasound or plain radiography. 


While anyone can produce kidney stones, certain people are more at risk for developing stones than others. Causes and risk factors for kidney stones include:

  • A family history of stone disease, especially in first degree relatives.

  • Dehydration - Lack of fluids can cause salts and other minerals in the urine to stick together to cause kidney stones.

  • Certain diets - Diets high in protein, salt, oxalates (such as spinach, chocolate, nuts), excess vitamin C or D can increase your risk of developing kidney stones.

  • Certain medical conditions - Gastric conditions such as inflammatory bowel disease, Crohn's disease and chronic diarrhea affect the way the body absorbs water, calcium and oxalates, which increases levels of stone-forming substances in the urine.

  • Metabolic diseases (such as hyperparathyroidism or gout).

  •  Obesity has been linked to higher incidences of stone formation. 

Learn More:

Treatment options for kidney stones

Metabolic evaluation for stone disease

Kidney stone prevention