Educational contents


What is dialysis?

Dialysis is the artificial process of eliminating waste and unwanted water from the blood. Our kidneys do this naturally. However, some people 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.

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.

Dialysis is also used to rapidly remove toxins or drugs from the blood. There are two main types of dialysis - hemodialysis and peritoneal dialysis What type of dialysis a patient should have really does depend on each individual case.


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.

Patients need to be prepared for hemodialysis. A blood vessel, usually in the arm, needs to be enlarged. Surgery is required for this. The enlarged vein makes the insertion of the catheters possible. US researchers have developed a new way of growing blood vessels using patients' own skin cells to seed the growth of tissue and have tested it in dialysis patients with end stage kidney disease.

Hemodialysis usually lasts about 3 to 4 hours each week. The duration of each session depends on how well the patient's kidneys work, and how much fluid weight the patient has gained between treatments.

peritoneal dialysis

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.

The dialysate is left there for some time so that it can absorb waste products. Then it is drained out through a tube and discarded. This exchange, or cycle, is generally repeated several times during the day. The elimination of unwanted water occurs through osmosis - as the dialysis solution has a high concentration of glucose, it results in osmotic pressure which causes the fluid to move from the blood into the dialysate. Consequently, a larger quantity of fluid is drained than introduced.

Peritoneal dialysis is done at home by the patient; by a willing and motivated patient. It gives the patient a greater amount of freedom and independence because he/she does not have to come in to the clinic at multiple times each week. It can also be done while traveling with a minimum of specialized equipment.

Before having peritoneal dialysis, the patient needs to have a small surgical procedure to insert a catheter into the abdomen. This is kept closed off, except when fluid is being introduced or taken out of the abdomen.

Renal Transplantation

What is renal transplantation (kidney transplantation)?

Renal transplantation (kidney transplantation) is the organ transplant of a kidney into a patient with end-stage renal disease. Renal transplantation is typically classified as deceased-donor (formerly known as cadaveric) or living-donor transplantation depending on the source of the donor organ.

Kidney disease

What are the symptoms of kidney failure?

Kidney failure tends to happen gradually. Even if just one kidney works, or both work partially, normal kidney function is still possible. So, it can be a very long time before any symptoms are noticed by the patient. The following symptoms may be present:

  • Fatigue (tiredness)
  • Frequent need to urinate, especially at night. Frequency grows with time
  • Itchy skin
  • Erectile dysfunction (men have difficulty getting and/or sustaining an erection)
  • Nausea
  • Shortness of breath
  • Water retention (swollen feet, hands, ankles)
  • Blood in urine
  • Protein in urine

A sudden injury can cause kidney failure. When it does, symptoms tend to appear faster, and progress more rapidly as well.

Anemia - People with chronic kidney disease are usually affected by anemia (90% of them). When levels of EPO (erythropoietin), which is produced by the kidneys, are low, anemia can develop. EPO makes the body produce red blood cells. When your red blood cell count is low you have anemia. Chronic kidney failure patients who have anemia are usually given an ESA (erythropoiesis-stimulating agent) injection.

What are the causes of kidney disease?

  • Diabetes - thought to cause about half of all cases
  • Hypertension (high blood pressure) - thought to cause about one quarter of all cases
  • Inflammation of the kidney (glomerulonephritis)
  • Malaria
  • Long-term exposure to lead, solvents and fuels
  • Systemic lupus erythematosus - body's own immune system attacks the kidneys
  • Polycystic kidney disease - inherited
  • Physical injury, such as a heavy blow to the kidney
  • Kidney infection (pyelonephritis)
  • Cardiac and vascular surgery
  • Jaundice
  • Over consumption of some medications
  • Unborn baby does not have normally developing kidneys
  • Yellow fever