You have two kidneys. These organs are small, shaped like a bean and perform many important functions. They're located just below the ribs, one kidney on each side of your body. If the kidneys lose some ability to function, you may not have any symptoms or problems at all. Because kidney disease can exist without causing symptoms, if you think you are at risk, your doctor can perform a simple blood test to determine how well your kidneys are working.
Blood Filtration
According to the National Kidney and Urologic Diseases Information Clearinghouse, "Every day, a person's kidneys process about 200 quarts of blood..." This blood must be filtered so that waste products can be removed and essential components can be returned to the body. After you eat, your body breaks down the food for fuel. Waste products (salts, toxins, and water) that are produced are sent to your liver. Structures located inside your kidneys called nephrons help in this process. The waste products are converted to urine and excreted from the body.
Regulation of Electrolytes and Water Balance
The Massachusetts Institute of Technology says your kidneys maintain and adjust the level of fluids in the body. "It accomplishes this by excreting excessive amounts of water in the urine if body fluids are too dilute or by excreting excessive solutes when body fluids are too concentrated." During this process, your kidneys also maintain balance by ensuring your blood doesn't become too acidic or alkaline.
Additional Functions
The kidneys are responsible for releasing three hormones--erythropoietin, which supports your body in making red blood cells; renin, which regulates blood pressure; and calcitriol, which helps your bones maintain calcium. According to the Nemours Foundation, "By regulating salt levels through production of an enzyme called renin (as well as other substances), the kidneys ensure that blood pressure is regulated."
