Two of the kidneys’ most important jobs are to filter wastes out of your blood and to form urine to carry these wastes out of your body. As part of this process, kidneys adjust the amounts of the following in your blood:

• Water
• Minerals (including calcium and phosphorus)
• Electrolytes (sodium, potassium and chloride)

Maintaining your body’s balance of water, minerals and electrolytes is very complex. But most of the wastes, minerals and electrolytes that your kidneys remove come from the foods you eat. When you digest protein, your body forms a waste product called urea. Urea and other wastes combine with water in your kidneys to form urine.

Most people have two kidneys — one on each side of the lower back. Some people can live fairly normal lives with only one healthy kidney. But a damaged or diseased kidney may not be able to filter enough waste from the blood. If this happens, wastes and electrolytes can build up in the blood and act like poison.

If you have kidney disease (also called renal disease), your kidneys don’t filter enough waste from your blood. The most common causes are diabetes, high blood pressure, hereditary kidney diseases, drug side effects and kidney stone blockage. People can lose more than half their normal kidney function before they start to notice symptoms of kidney disease. Some of these symptoms include nausea, vomiting, tiredness and loss of appetite.

When your kidneys can no longer remove waste products and excess fluids from your body, these wastes and fluids can build up and poison your body. Hemodialysis* is the process of removing excess urea, fluid, electrolytes, minerals and other wastes from your body when your kidneys can’t. Several times a week when you have dialysis, your blood passes through a machine’s special filter that removes water, waste products, minerals and electrolytes from your blood. In addition to treatment, and to help prevent the buildup of wastes and fluids between dialysis treatments, you may need to limit your intake of certain foods and fluids.