What Is It?

The kidneys are a pair of bean-shaped, fist-sized organs below the rib cage in the back of the abdomen. One sits on each side of the spine. They filter waste products, excess water, and salt from the blood. These organs regulate the body's balance of fluids and minerals such as potassium and sodium. They also produce hormones that monitor blood pressure and regulate the production of red blood cells.

Patients whose kidneys have failed or don't work well generally need dialysis or a kidney transplant. During dialysis, a machine takes on the job of filtering waste products from the blood.