Dialysis is where a machine is used to replace a kidney after kidney failure. The word dialysis comes from the Greek word dialusis, dia meaning through, and lusis meaning loosening.
Dialysis can be used for people who have become sick and have lost the use of their kidneys for a short time, or for people who no longer have working kidneys. The purpose of the kidney is to keep a balance of water and minerals in the body. These minerals include sodium, potassium, chloride, calcium, phosphorous, magnesium and sulfate. The kidneys also take out hydrogen ions from the blood. Dialysis is able to remove these wastes from the body and help keep the minerals in balance.
However the kidneys are also part of the endocrine system and make erythropoietin and calcitriol. Dialysis machines are not able to replace this part of the kidney's function.