The kidneys are a pair of small, bean-shaped organs. They are located towards the back of the torso, behind the lower ribs.
The primary function of the kidneys is to filter blood for the removal of waste products. Wastes are expelled from the kidneys as urine, which travel out of the kidneys via tubes called ureters that connect to the bladder.
Occasionally, calculi or crystals form in a kidney and are referred to as kidney stones. These are a combination of calcium, uric acid and other substances found in urine. Many people pass small kidney stones from their bodies without any symptoms, but larger stones can be very painful as they move through the ureter, into the bladder, and out of the body.
Changes in diet may help to reduce the risk for kidney stones. Management by a doctor to treat and prevent kidney stones is recommended for patients at risk.