About the kidneys
Most everyone is born with two kidneys that weigh about five ounces each and are the size of your fist. They are located underneath your ribs, which protect them.
Healthy kidneys are always working. They filter waste products and remove extra fluid from the blood and balance chemical levels in the bloodstream. Kidneys also release hormones that control blood pressure and other functions, such as erythropoietin, which produces red blood cells, and calcitriol, which keeps bones healthy.
Chronic kidney failure
Kidneys that function at 15 percent or less produce chronic kidney failure or end-stage renal disease. There are several diseases that cause end-stage renal disease. The most common contributor is Type 2 diabetes, followed by high blood pressure.