Several different types of kidney stones

Kidney stones are small chunks of solid material that can form in your kidneys, a pair of organs that filter your blood.

The “stones,” which are usually yellow and brown, vary in size and shape.

For instance, some may be jagged and as small as a grain of sand, while others may be lumpy and the size of golf balls.

A stone may stay in the kidney or travel down the urinary tract — the body’s waste and excess-water drainage system — and get stuck, causing severe pain in the belly or side of the back.

Other symptoms may include nausea, chills, and blood in the urine.

 

Prevalence and Demographics of Kidney Stones

Kidney stones are one of the most common disorders of the urinary tract, resulting in more than a million visits to health care providers and 300,000 emergency room visits each year in the United States, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).

About one in 11 people in the United States, or 8.8 percent of the population, have had a kidney stone, according to a 2012 report in the journal European Urology.

Kidney stones affect both men and women, though struvite stones are more common in women and uric acid stones are more common in men.

Overall, however, the prevalence of kidney stones is higher in men than women.

Kidney stones are also more common in obese people than non-obese people, and less common in non-Hispanic African and Mexican-Americans than in non-Hispanic Caucasians, according to the European Urology study.

 

What Are the Kidneys?

Part of the urinary system, your two kidneys are fist-sized, bean-shaped organs, located just below the rib cage, one on each side of the spine.

They have a number of important functions, mainly filtering the blood to remove waste and excess water, resulting in the formation of urine, which is stored in the bladder and emptied from the body through the urethra.

The kidneys also:

  • Balance the body’s levels of electrolytes, including sodium, potassium, and phosphate, to maintain the body’s balance of acids and bases
  • Produce hormones involved in regulating blood pressure, producing red blood cells, and maintaining bone strength
  • Prevent the buildup of waste and fluid in the body