Dialysis is the artificial process of eliminating waste (diffusion) and unwanted water (ultrafiltration) from the blood. Our kidneys do this naturally. Some people, however, may have failed or damaged kidneys which cannot carry out the function properly – they may need dialysis.
In other words, dialysis is the artificial replacement for lost kidney function (renal replacement therapy).
Dialysis may be used for patients who have become ill and have acute kidney failure (temporary loss of kidney function), or for fairly stable patients who have permanently lost kidney function (stage 5 chronic kidney disease).
When we are healthy our kidneys regulate our body levels of water and minerals, and remove waste. The kidneys also produce erythropoietin and 1,25-dihydroxycholecalciferol (calcitriol) as part of the endocrine system. Dialysis does not correct the endocrine functions of failed kidneys – it only replaces some kidney functions, such as waste removal and fluid removal.