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

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.

Why is dialysis necessary?

Approximately 1,500 liters of blood are filtered by a healthy person's kidneys each day. We could not live if waste products were not removed from our kidneys. People whose kidneys either do not work properly or not at all experience a buildup of waste in their blood. Without dialysis the amount of waste products in the blood would increase and eventually reach levels that would cause coma and death.

What is hemodialysis?

The blood circulates outside the body of the patient - it goes through a machine that has special filters. The blood comes out of the patient through a catheter (a flexible tube) that is inserted into the vein. The filters do what the kidney's do; they filter out the waste products from the blood. The filtered blood then returns to the patient via another catheter. The patient is, in effect, connected to a kind of artificial kidney. It is a day care procedure takes 3-4 hours for each session of hemodialysis.

What is peritoneal dialysis?

A sterile (dialysate) solution rich in minerals and glucose is run through a tube into the peritoneal cavity, the abdominal body cavity around the intestine, where the peritoneal membrane acts as a semi-permeable membrane.

The abdomen is the area between the chest and hips - it contains the stomach, small intestine, large intestine, liver, gallbladder, pancreas and spleen. Peritoneal dialysis uses the natural filtering ability of the peritoneum - the internal lining of the abdomen. In other words, peritoneal dialysis uses the lining of the abdomen as a filter of waste products from the blood.