The kidneys are two beanshaped organs located below your chest, one on each side of the spine. The kidneys remove extra water and wastes from the blood, producing urine. They also produce hormones and keep a stable balance of salts in the blood. Narrow tubes called ureters carry urine from the kidneys to the bladder, an oval-shaped reservoir for urine in the abdomen.

A kidney stone is composed of crystals formed by chemicals that separate from the urine that builds up in the kidney.

The most common type of stone contains calcium oxalate or calcium phosphate. A less common type of stone, caused by infection in the urinary tract, is called a struvite stone. Other rarer stones include uric acid stones and cystine stones.