Kidneys are two bean-shaped organs, each about the size of fists. They are located near the middle of the back, just below the rib cage. Inside each kidney about a million tiny structures called nephrons filter blood. They remove waste products and extra water, which become urine. The urine flows through tubes called ureters to the bladder, which stores the urine until person goes to the bathroom. Most kidney diseases attack the nephrons. This damage may leave kidneys unable to remove wastes. Causes can include genetic problems, injuries, or medicines. Someone is at greater risk for kidney disease if s-he has diabetes, high blood pressure, or a close family member with kidney disease. Chronic kidney disease damages the nephrons slowly over several years. Other kidney problems include: Cancer; Cysts; Stones; Infections. If kidneys fail completely, a kidney transplant or dialysis can replace the work kidneys normally do.