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